See the Glossary of underwater diving terminology for definitions of technical terms, jargon, diver slang and acronyms used in underwater diving

See the Outline of underwater diving for a hierararchical listing of underwater diving related articles

See the Index of underwater divers for an alphabetical listing of articles about underwater divers

See the Index of recreational dive sites for an alphabetical listing of articles about places which are recreational dive sites

The following index is provided as an overview of and topical guide to underwater diving:

Surface-supplied divers riding a stage to the underwater workplace

Underwater diving can be described as all of the following:

• A human activity – intentional, purposive, conscious and subjectively meaningful sequence of actions. Underwater diving is practiced as part of an occupation, or for recreation, where the practitioner submerges below the surface of the water or other liquid for a period which may range between seconds to order of a day at a time, either exposed to the ambient pressure or isolated by a pressure resistant suit, to interact with the underwater environment for pleasure, competitive sport, or as a means to reach a work site for profit or in the pursuit of knowledge, and may use no equipment at all, or a wide range of equipment which may include breathing apparatus, environmental protective clothing, aids to vision, communication, propulsion, maneuverability, buoyancy and safety equipment, and tools for the task at hand.

1 – 9[edit]

• 
  1982 invasion of the Falkland Islands – Argentine invasion of the Falkland Islands starting the Falklands War

A[edit]

• 
  AAI underwater revolver – Six-round amphibious revolver for naval use


• 
  ADS amphibious rifle – Russian bullpup assault rifle for combat divers


• 
  Advanced Open Water Diver – Recreational scuba diving certification slightly above minimum entry level


• 
  Advanced SEAL Delivery System – Former Navy SEAL mini-sub deployed from submarines


• 
  Aerospace Medical Association – A professional organization in aviation, space, hyperbaric and environmental medicine


• 
  AIDA Hellas – National representative of AIDA International in Greece


• 
  AIDA International (AIDA) – Worldwide rule- and record-keeping body for competitive breath-hold events


• 
  Airlift (dredging device) – Dredging device using injected air to move water and entrained load up a pipe


• 
  Algal bloom – Rapid increase or accumulation in the population of planktonic algae


• 
  Alternative air source – Emergency supply of breathing gas for an underwater diver


• 
  Altitude diving – Underwater diving at altitudes above 300 m


• 
  Ambient pressure – Pressure of the surrounding medium


• 
  American Academy of Underwater Sciences (AAUS) – Organization responsible for standards for American scientific diving certification and operation of scientific diving programs


• 
  American Canadian Underwater Certifications (ACUC) – Recreational diver training and certification agency


• 
  American Nitrox Divers International (ANDI) – Recreational diver training and certification agency


• 
  Amontons' law – Any one of several discoveries about thermal expansion of gases and the relationship betweenre


• 
  Anti-fog – Chemicals that prevent the condensation of water as small droplets on a surface


• 
  Anti-frogman techniques – Methods of protection against incursions by underwater divers and swimmers


• 
  Apnea finswimming – Underwater swimming in a swimming pool using mask, monofin and holding one's breath.


• 
  APS underwater rifle – Soviet underwater assault firarm firing unrifled steel flechettes


• 
  Aquanaut – Diver who remains at depth underwater for longer than 24 hours


• 
  Aquarium diving – Occupational diving in large aquariums


• 
  Aquathlon (underwater wrestling) – Competitive underwater wrestling


• 
  Archimedes' principle – Buoyancy principle in fluid dynamics


• 
  Army engineer diver – Members of national armies who are trained to undertake reconnaissance, demolition, and salvage tasks underwater


• 
  Army Ranger Wing – Special operations force of the Irish Defence Forces


• 
  Air embolism, also known as Arterial gas embolism – Vascular blockage by air bubbles


• 
  Alternobaric vertigo – Dizziness resulting from unequal pressures in the middle ears


• 
  Artificial gills (human) – Hypothetical devices to allow a human to take in oxygen from surrounding water


• 
  Artificial Reef Society of British Columbia (ARSBC) – Canadian non-profit to create artificial reefs for habitat enhancement and recreation


• 
  Ascending and descending (diving) – Procedures for safe ascent and descent in underwater diving


• 
  ASM-DT amphibious rifle – Russian folding stock underwater firearm


• 
  Association nationale des moniteurs de plongée (ANMP) – French recreational diver training and certification agency


• 
  Atmospheric diving suit – Articulated pressure resistant anthropomorphic housing for an underwater diver


• 
  Atmospheric pressure – Static pressure exerted by the weight of the atmosphere


• 
  Atmospheric pressure diving – Articulated pressure resistant anthropomorphic housing for an underwater diver


• 
  Australian Diver Accreditation Scheme (ADAS) – Australian based international occupational diver accreditation organisation


• 
  Australian Underwater Federation (AUF) – The governing body for underwater sports in Australia


• 
  Autonomous diver – International minimum standard for entry level recreational scuba diver certification


• 
  Autonomous Robotics Ltd – UK company developing an autonomous underwater vehicle


• 
  AUV-150 – An unmanned underwater vehicle in development in by Central Mechanical Engineering Research Institute


• 
  AUV Abyss – An autonomous underwater vehicle for mapping of the seabed and water column data collection


• 
  Autonomous underwater vehicle – Unmanned underwater vehicle with autonomous guidance system


• 
  Avascular necrosis – Death of bone tissue due to interruption of the blood supply

B[edit]

• 
  Bachrach, Arthur J. – American psychologist and administrator


• 
  Backplate and wing – Type of back-mount scuba harness


• 
  Barotrauma – Injury caused by pressure


• 
  Behnke, Albert R. – US Navy physician and diving medicine researcher


• 
  Bellman (diving) – The member of a dive team who acts as stand-by diver and tender from the diving bell


• 
  Bert, Paul – French zoologist, physiologist and politician


• 
  Blood–air barrier – Membrane separating alveolar air from blood in lung capillaries


• 
  Blood shift represented by Diving reflex#Blood shift – redistributed blood flow from the extremities to the head and torso during a breath-hold dive.


• 
  Boat diving – Procedures specific to diving from boats


• 
  Boaty McBoatface – Autonomous underwater vehicle (AUV) for scientific research to be carried on the RRS Sir David Attenborough


• 
  Bond, George F. – US Navy physician and diving medicine and saturation diving researcher


• 
  Booster pump – Machine to increase pressure of a fluid


• 
  Boyle, Robert – Anglo-Irish natural philosopher, chemist, physicist, and inventor


• 
  Boyle's law – Relationship between pressure and volume in a gas at constant temperature


• 
  Breaking wave, also known as surf – A wave that becomes unstable as a consequence of excessive steepness


• 
  Breathing – Process of moving air into and out of the lungs


• 
  Breathing gas – Gas used for human respiration


• 
  Breathing performance of regulators – Measurement and requirements of work of breathing of diving regulators


• British commando frogmen


• 
  British Freediving Association (BFA) – British affiliate to AIDA International


• 
  British Octopush Association (BOA) – National body for underwater hockey in the United Kingdom


• 
  British Sub-Aqua Club (BSAC) – Recreational diving club, training and certification agency based in the UK


• 
  British Underwater Sports Association (BUSA) – British affiliate to the world underwater federation sports committee.


• 
  Buddy breathing – Technique for sharing breathing gas from a single mouthpiece


• 
  Buddy check – Pre-dive safety checks carried out by two-diver dive teams


• 
  Buddy diving – Practice of mutual monitoring and assistance between two divers


• 
  Bühlmann, Albert A. – Swiss physician and decompression researcher


• 
  Bühlmann decompression algorithm, also known as Buhlmann algorithm – Algorithm for modelling of inert gases entering and leaving body tissues in solution as pressure changes


• 
  Built-in breathing system (BIBS) – System for supply of breathing gas on demand within a confined space


• 
  Buoyancy – An upward force that opposes the weight of an object immersed in fluid


• 
  Buoyancy compensator (BCD), also known as Buoyancy control device – Diving equipment for controlling buoyancy by volume adjustment


• 
  Burst disc, also known as rupture disc – A non-closing over-pressure relief device


• 
  Byford Dolphin#Diving bell accident – Explosive decompression of saturation system on semi-submersible offshore drilling rig

C[edit]

• 
  Canadian armed forces divers – Underwater divers employed by any of the Canadian armed forces


• 
  Canoe and kayak diving – Recreational diving from a canoe or kayak


• 
  Carbon dioxide retention – A tendency to retain abnormally high tissue carbon dioxide levels


• 
  Carbon dioxide scrubber – Device which absorbs carbon dioxide from circulated gas


• 
  Carbon monoxide poisoning – Toxic effects of carbon monoxide


• 
  Carleton CDBA – Military rebreather by Cobham plc


• 
  Cascade filling system – Filling pressurised gas from a series of storage cylinders


• 
  Cave Divers Association of Australia (CDAA) – Association to represent cave divers and administrate and support cave diving in Australia


• 
  Cave diving – Underwater diving in water-filled caves


• 
  Cave Diving Group (CDG) – UK based cave diver training and certification agency


• 
  Cenote – A natural pit, or sinkhole, that exposes groundwater underneath


• 
  HMS Challenger K07 – Royal Navy saturation diving support vessel


• 
  Chamber operator – A person who operates a diving chamber


• 
  Charles's law – Relationship between volume and temperature of a gas at constant pressure


• 
  Checklist – An aide-memoire to ensure consistency and completeness in carrying out a task


• 
  Christ of the Abyss – A submerged bronze statue of Jesus Christ in the Mediterranean Sea


• 
  Circulatory system – Organ system for circulating blood in animals


• 
  Cis-Lunar – Manufacturer of electronically controlled closed-circuit rebreathers for scuba diving


• 
  Civil liability in recreational diving – Legal duty of care, negligence and liability in recreational diving


• 
  Clarke, John R. – American scientist and underwater breathing apparatus authority


• 
  Clearance diver – Navy diver specialist with explosives


• 
  Clearance Divers Life Support Equipment (CDLSE) – British military electronically controlled closed circuit rebreather


• 
  Clearance Diving Branch (RAN) – Diving unit of the Royal Australian Navy


• 
  CMAS* SCUBA Diver – Entry level recreational diving certification from CMAS


• 
  CMAS Europe – Non-profit branch of the world underwater federation representing European affiliates


• 
  CMAS Scientific Committee – International organisation for underwater activities in sport and science, and recreational diver training and certification


• 
  Code of practice – A set of written rules which specifies how people working in a particular occupation should behave


• 
  Cold shock response – Physiological response to sudden exposure to cold


• 
  Comando Raggruppamento Subacquei e Incursori Teseo Tesei – Italian special forces diving unit


• 
  Combat Rubber Raiding Craft – Rubberised fabric tactical inflatable boat used by the US Navy


• 
  Combat sidestroke – Variation of side-stroke swimming used by United States Navy SEALs


• 
  Combined gas law – Ideal gas law combining Charles's law, Boyle's law, and Gay-Lussac's law


• 
  Comhairle Fo-Thuinn (CFT) – Irish national governing body for recreational diving and underwater sport.


• 
  Commandos Marine – Special operations forces of the French Navy


• 
  Commercial diver training – Processes by which people develop the skills and knowledge to dive safely for industrial applications


• 
  Commercial diving – Professional diving on industrial projects


• 
  Commercial offshore diving – Professional diving in support of the oil and gas industry


• 
  Competitive apnea – Competitive breathhold diving


• 
  Compression arthralgia – Joint pain caused by fast compression to high ambient pressure


• 
  Confédération Mondiale des Activités Subaquatiques (CMAS) – International organisation for underwater activities in sport and science, and recreational diver training and certification


• 
  Constant weight apnea – Freediving discipline in which the diver descends and ascends only by swimming with the use of fins


• 
  Constant weight without fins – Freediving discipline in which the diver descends and ascends only by swimming without the use of fins


• 
  Controlled buoyant lift – A technique used by scuba divers to raise an incapacitated diver to the surface


• 
  Controlled emergency swimming ascent – A technique used by scuba divers to return to the surface in an out-of-gas emergency in shallow water


• 
  Cosmos CE2F series – Italian swimmer delivery vehicles


• 
  Counterlung – Variable volume component in a rebreather to take up and release gas during a breathing cycle


• 
  Cryogenic rebreather – Rebreather that removes CO2 by freezing it out using heat exchange with liquid oxygen


• 
  CUMA – Canadian military diving rebreather


• 
  Current (stream) – Flow of water in a river due to gravity


• 
  Cylinder valve alias Pillar valve represented by Diving cylinder#The cylinder valve – valve to control gas flow to and from a cylinder and to connect with the regulator or filling hose

D[edit]

• 
  Dalton's law – Gas law describing pressure contributions of component gases in a mixture


• 
  The Darkness Beckons – A history of UK cave diving by Martyn Farr


• 
  Davis Submerged Escape Apparatus – Early submarine escape oxygen rebreather also used for shallow water diving.


• 
  Dead space (physiology) – The volume of inhaled air that does not take part in the gas exchange


• 
  Decima Flottiglia MAS – Italian naval commando frogman unit of the Fascist era


• 
  Decompression buoy – Inflatable surface marker buoy deployed from underwater


• 
  Decompression (diving) – The reduction of ambient pressure on underwater divers after hyperbaric exposure and the elimination of dissolved gases from the diver's tissues


• 
  Decompression equipment – Equipment used by divers to facilitate decompression


• 
  Decompression illness – Disorders arising from ambient pressure reduction


• 
  Decompression practice – Techniques and procedures for safe decompression of divers


• 
  Decompression sickness – Disorder caused by dissolved gases in the tissues forming bubbles during reduction of the surrounding pressure


• 
  Decompression theory – Theoretical modelling of decompression physiology


• 
  Decompression trapeze – Horizontal bars suspended at decompression stop depths


• 
  DeepC – Autonomous underwater vehicle powered by a fuel cell


• 
  Deep diving – Underwater diving to a depth beyond the norm accepted by the associated community


• 
  Diamond Reef System – System for training divers in buoyancy, trim and maneuvering skills


• 
  DEPTHX – Autonomous underwater vehicle for exploring sinkholes in Mexico


• 
  Diffusion – Statistical movement of molecules or atoms from a region of high concentration to a region of low concentration


• 
  Distance line/dive reel/guide line – Line deployed by scuba divers for navigation


• 
  Dive boat – Boat used for the support of scuba diving operations


• 
  Dive computer, also known as Decompression computer – Instrument to record dive profile and calculate decompression obligations in real time


• 
  Dive guide – A recreational dive leader certification and role


• 
  Dive light – Light used underwater by a diver


• 
  Dive log – Record of diving history of an underwater diver


• 
  Divemaster – Recreational dive leader certification and role


• 
  Dive planning – The process of planning an underwater diving operation


• 
  Dive team – A group of people working together to enhance dive safety and achieve a task


• 
  Diver certification – Certification as competent to dive to a specified standard


• 
  Diver communications – Methods used by underwater divers to communicate


• 
  Diver down flag – Flag signal indicating divers are in the water nearby


• 
  Diver navigation – Underwater navigation by scuba divers


• 
  Diver propulsion vehicle (DPV | Diver propulsion vehicle]] (DPV]]


• 
  Diver rescue – Rescue of a distressed or incapacitated diver


• 
  Diver training – Processes by which people develop the skills and knowledge to dive safely underwater


• 
  Diver trim – Balance and orientation skills of an underwater diver


• 
  Divers Alert Network (DAN) – International group of not-for-profit organizations for improving diving safety


• 
  Diver's attendant – The member of a dive team who assists the diver at the surface and tends the diver's umbilical or lifeline


• 
  Divers Institute of Technology – A private, commercial educational institution for the training of commercial divers


• 
  Diver's pump – Manually powered surface air supply for divers


• 
  Diver's umbilical – A hose and cable bundle which supplies breathing gas, communications and other services to a diver


• 
  Diving air compressor, also known as Diving compressor – Machine used to compress breathing air for use by underwater divers


• 
  Diving bell – Chamber for transporting divers vertically through the water


• 
  Diving chamber – Hyperbaric pressure vessel for human occupation used in diving operations


• 
  Diving cylinder – High pressure compressed gas cylinder used to store and supply breathing gas for diving


• 
  Diving Diseases Research Centre (DDRC) – British hyperbaric medical organisation


• 
  Diving disorders – Physiological disorders resulting from underwater diving


• 
  Diving equipment – Equipment used to facilitate underwater diving


• 
  Diving Equipment and Marketing Association (DEMA) – International trade association for the recreational diving equipment industry


• 
  Diving hazards – The hazards to which an underwater diver may be exposed


• 
  Diving helmet – Rigid head enclosure with breathing gas supply worn for underwater diving


• 
  Diving instructor – Person who trains and assesses underwater divers


• 
  Diving mask – Watertight air-filled face cover with view-ports for improving underwater vision


• 
  Diving Medical Advisory Council (DMAC) – Independent organisation of diving medical specialists from Northern Europe


• 
  Diving medical examiner – A medical practitioner registered to assess medical fitness to dive


• 
  Diving medical practitioner – A medical practitioner with registered to assess medical fitness to dive, manage diving accidents, plan safety for professional diving operations, provide advanced life support, acute trauma care and general wound care.


• 
  Diving medical technician – a member of a dive team who is trained in advanced first aid and fit to provide treatment in a hyperbaric chamber in an emergency


• 
  Diving medicine – Diagnosis, treatment and prevention of disorders caused by underwater diving


• 
  Diving physics – Aspects of physics which affect the underwater diver


• 
  Diving reflex – The physiological responses to immersion of air-breathing vertebrates


• 
  Diving regulator – Mechanism that reduces pressure of a gas supply and provides it to the diver at ambient pressure


• 
  Diving safety – Safety of underwater diving activities


• 
  Diving Science and Technology (DSAT) – PADI affiliate and developer of recreational decompression planning tools


• 
  Diving shot, also known as Shot line – Substantial weighted near-vertical line with buoy


• 
  Diving stage – A platform on which one or two divers stand which transports them vertically through the water


• 
  Diving suit – Garment or device designed to protect a diver from the underwater environment


• 
  Diving supervisor – Professional diving team leader responsible for safety


• 
  Diving support vessel – A ship used as a floating base for professional diving projects


• 
  Diving systems technician – A competent person who maintains and repairs diving life-support equipment


• 
  Diving weight – Ballast carried by a diver to counteract buoyancy or adjust trim


• 
  Diving weighting system – Ballast carried by underwater divers to counteract buoyancy


• 
  Doing It Right (scuba diving) (DIR) – Technical diving safety philosophy


• 
  Dräger Dolphin – Semi-closed circuit recreational diving rebreather


• 
  Dräger Ray – Semi-closed circuit recreational diving rebreather designed to use standard nitrox breathing gas mixtures


• 
  Drift diving – Scuba diving where the diver is intentionally transported by the water flow


• 
  Drill Master diving accident – Fatal diving bell accident off Norway in 1974


• 
  Drowning – Respiratory impairment resulting from being in or under a liquid


• 
  Dry suit – Watertight clothing that seals the wearer from cold and hazardous liquids


• 
  Duty of care – A legal obligation to provide a standard of reasonable care when performing an activity that could foreseeably harm others


• 
  Dynamic apnea – Freediving disciplines where the breath-hold diver swims horizontally under water with or without fins


• 
  Dysbaric osteonecrosis – Ischemic bone disease caused by decompression bubbles


• 
  Dysbarism – Medical conditions resulting from changes of ambient pressure.

E[edit]

• 
  Ear clearing – Equalising of pressure in the middle ears


• 
  Eelume – Autonomous underwater vehicle being developed by Eelume AS


• 
  SS Egypt#Salvage – Salvage of gold bullion from wreck using an armoured observation bell


• 
  Ekman transport – Net transport of surface water perpendicular to wind direction


• 
  Electro-galvanic oxygen sensor – Device which produces a voltage by a chemical reaction with oxygen proportional to partial pressure


• 
  Emergency ascent – An ascent to the surface by a diver in an emergency


• 
  Emergency gas supply – Alternative independent breathing gas supply carried by a diver.


• 
  Emergency Response Diving International (ERDI) – American organisation for training and certification of emergency response divers


• 
  Equivalent air depth – Method of comparing decompression requirements for air and a given nitrox mix


• 
  Equivalent narcotic depth – Method for comparing the narcotic effects of a trimix diving gas with air


• 
  European Diving Technology Committee (EDTC) – International organisation for improving professional diver safety


• 
  European Underwater and Baromedical Society (EUBS) – Source of information for diving and hyperbaric medicine


• 
  European Underwater Federation (EUF) – Ubrella organisation representing scuba diver training organisations in Europe


• 
  Evacuation plan – Removal of personnel from a high risk area or a developing incident to a safer place


• 
  Exercise Paddington Diamond – A joint Bolivian-British-Swiss scuba diving expedition to Lake Titicaca


• 
  Explorer AUV – Autonomous underwater vehicle from People's Republic of China


• 
  Explosive ordnance disposal (United States Navy) – US Navy personnel who render safe or detonate unexploded ordnance

F[edit]

• 
  Federación Española de Actividades Subacuáticas (FEDAS) – Spanish national federation for underwater activities, affiliated to CMAS


• 
  Fédération Française d'Études et de Sports Sous-Marins (FFESSM) – French diver training and certification agency


• 
  Federazione Italiana Attività Subacquee (FIAS) – Italian non-profit recreational diver training organisation affiliated to CMAS


• 
  Fife, William Paul – US Air Force officer and hyperbaric medicine researcher


• 
  Finning techniques – Techniques used by divers and surface swimmers using swimfins


• 
  Finswimming – Competitive watersport using swimfins for propulsion


• 
  Finswimming at the 2009 Asian Indoor Games – Competition held in Mỹ Đình National Aquatics Sports Complex, Hanoi, Vietnam


• 
  Force – Any interaction that, when unopposed, will change the motion of an object


• 
  Fraction of inspired oxygen – Volumetric proportion of oxygen to other constituents in a breathing gas


• 
  Freediving – Underwater diving without breathing apparatus


• 
  Freediving blackout – Loss of consciousness caused by cerebral hypoxia towards the end of a breath-hold dive


• 
  Free immersion apnea – Freediving discipline in which no propulsion equipment is used, but pulling on the rope during descent and ascent is permitted


• French commando frogmen


• 
  Frogman – Tactical scuba divers


• 
  FROGS – Closed circuit oxygen diving rebreather


• 
  Full face diving mask – Diving mask that covers the mouth as well as the eyes and nose

G[edit]

• 
  Gas blending – Producing special gas mixtures to specification


• 
  Gas blending for scuba diving – Mixing and filling cylinders with breathing gases for use when scuba diving


• 
  Gas exchange – The process by which gases diffuse through a biological membrane


• 
  Gay-Lussac's law – Any one of several discoveries about thermal expansion of gases and the relationship betweenre


• 
  Global Underwater Explorers (GUE) – Recreational/technical scuba training and certification agency


• 
  Goldfinder – Autobiography of British diver and treasure hunter Keith Jessop


• 
  Gradient factor in decompression modelling – A way for users to adjust the conservatism of a decompression algorithm in software


• 
  Green Fins – Organisation in South East Asia for preservation of coral reefs by improving diver behavior


• 
  GRUMEC, also known as Brazilian commando frogmen – Brazilian Navy special forces diving unit


• 
  Gyrojet – Firearm that fires small rocket projectiles

H[edit]

• 
  Halcyon PVR-BASC – Semi-closed circuit depth compensated passive addition diving rebreather


• 
  Halcyon RB80 – Non-depth-compensated passive addition semi-closed circuit rebreather


• 
  Haldane, John Scott – Scottish physiologist and decompression researcher


• 
  Haldane's decompression model – Decompression model developed by John Scott Haldane


• 
  Halocline – Stratification of a body of water due to salinity differences


• 
  Hamilton, Robert William Jr. – American physiologist and researcher in hyperbaric physiology.


• 
  Hawaiian sling – Simple form of underwater speargun


• 
  Hazard analysis (HAZID) – The identification of present hazards as the first step in a process to assess risk


• 
  Hazardous Materials Identification System – A numerical hazard rating using colour coded labels


• 
  Hazmat diving – Underwater diving in a known hazardous materials environment


• 
  Health and Safety Executive (HSE) – Organisation responsible for the encouragement, regulation and enforcement of workplace health, safety and welfare in Great Britain


• 
  Heckler & Koch P11 – Five-barreled underwater rocket dart pistol


• 
  Heliox – A breathing gas mixed from helium and oxygen


• 
  Henry's law – Relation of equilibrium solubility of a gas in a liquid to its partial pressure in the contacting gas phase


• 
  Hierarchy of hazard controls – System used in industry to eliminate or minimize exposure to hazards


• 
  High-pressure nervous syndrome – A reversible diving disorder that occurs when a diver descends below about 150 m using a breathing gas based on helium


• 
  High-pressure water jetting – The use of very high pressure water for removing contamination and coatings from hard surfaces


• 
  Hill, Leonard Erskine – British physiologist and diving physiology researcher


• 
  Hills, Brian Andrew – Physiologist who worked on decompression theory


• 
  Historical Diving Society – UK based organisation to conserve diving heritage


• 
  History of decompression research and development – A chronological list of notable events in the history of underwater diving.


• 
  History of scuba diving – History of diving using self-contained underwater breathing apparatus


• 
  History of underwater diving – History of the practice of descending below the water's surface to interact with the environment


• 
  Hoppe-Seyler, Felix – German physiologist and chemist


• 
  Hot water suit – A wetsuit with a supply of heated water to keep a diver warm


• 
  Human factors in diving safety – The influence of physical, cognitive and behavioral characteristics of divers on safety


• 
  Human torpedo – Early form of diver propulsion vehicle


• 
  Hydrogen narcosis – Psychotropic state induced by breathing hydrogen at high partial pressures


• 
  Hydrogen sulfide – Poisonous, corrosive and flammable gas


• 
  Hydrophobe – A molecule or surface that has no attraction to water


• 
  Hydrostatic pressure – The static pressure exerted by the weight of the fluid column above the point


• 
  Hydrostatic test – Non-destructive test of pressure vessels


• 
  Hyperbaric medicine – Medical treatment in which an ambient pressure greater than sea level atmospheric pressure is a necessary component


• 
  Hyperbaric stretcher – Portable pressure vessel to transport a person under pressure.


• 
  Hyperbaric treatment schedules – Planned sequences of hyperbaric pressure exposure using a specified breathing gas as medical treatment


• 
  Hyperbaric welding – Welding metal at elevated pressure


• 
  Hypercapnia – Abnormally high tissue carbon dioxide levels


• 
  Hypocapnia – A state of reduced carbon dioxide in the blood


• 
  Hypothermia – A human body core temperature below 35.0°C


• 
  Hypoxia (medical) – A condition in which the body or a region of the body is deprived of adequate oxygen at the tissue level

I[edit]

• 
  Ice diving – Underwater diving under ice


• 
  IDA71 – Russian military rebreather for underwater and high altitude use


• 
  Ideal gas law – The equation of state of a hypothetical ideal gas


• 
  Immersion finswimming – Underwater swimming using mask, monofin and underwater breathing apparatus in a swimming pool


• 
  Incident pit – Conceptual model for explaining incident development and recovery


• 
  INSFOC, also known as Indonesian Navy Special Force and Operations Command – Indonesian Navy Special Force and Operations Command


• 
  Integrated Diver Display Mask – Diving half-mask with integrated head-up instrument display


• 
  Intelligent Water class AUV – Autonomous underwater vehicle for the People's Liberation Army Navy


• 
  International Association for Handicapped Divers (IAHD) – Non-profit organisation based in the Netherlands


• 
  International Association of Nitrox and Technical Divers (IANTD) – Recreational and technical scuba training and certification agency


• 
  International Diving Educators Association (IDEA) – Recreational scuba training and certification agency


• 
  International Diving Regulators and Certifiers Forum (IDRCF) – International forum of professional diver accreditation organisations


• 
  International Diving Schools Association (IDSA) – Organisation to develop common standards for commercial diver training


• 
  International Marine Contractors Association (IMCA) – International trade association for the marine contracting industry


• 
  International Organization for Standardization (ISO) – An international standard-setting body composed of representatives from national standards organizations


• 
  Interspiro DCSC – Military seem-closed circuit passive addition diving rebreather


• 
  Intervention AUV – Type of autonomous underwater vehicle capable of autonomous interventions


• 
  Introductory diving – Introductory scuba diving experience


• 
  Investigation of diving accidents – Forensic investigation of underwater diving accidents


• 
  In-water recompression – In-water treatment for decompression sickness


• 
  iRobot Seaglider – Deep diving autonomous underwater vehicle for long term missions


• 
  Isobaric counterdiffusion – Diffusion of gases into and out of biological tissues under a constant ambient pressure after a change of gas composition


• 
  Israeli Diving Federation (TIDF) – Israeli recreational diver training and certification agency


• 
  Italian auxiliary ship Olterra – Salvaged Italian tanker used as support and base for WWII manned torpedo frogman raids on Allied shipping in Gibraltar

J[edit]

• 
  Job safety analysis (JSA) – Procedure to integrate safety practices into a particular task


• 
  Johnson Sea Link accident – Manned submersible incident in which two divers died


• 
  Jonline – A short line used by scuba divers to clip themselves to something

K[edit]

• 
  KISS – Manually controlled closed circuit diving rebreather


• 
  Kommando Spezialkräfte Marine – German postwar commando amphibious warfare force


• 
  KOPASKA – Indonesian Navy special operations and demolition unit


• 
  Kursk submarine disaster#Salvage operation – Raising the wreck of a Russian nuclear submarine

L[edit]

• 
  Lambertsen Amphibious Respiratory Unit – Early closed circuit oxygen diving rebreather.


• 
  Lambertsen, Christian J. – American environmental and diving medicine specialist and developer of an early rebreather


• 
  LAR-5 represented by Drägerwerk – German manufacturer of breathing equipment


• 
  LAR-6 represented by Drägerwerk – German manufacturer of breathing equipment


• 
  LAR-V represented by Drägerwerk – German manufacturer of breathing equipment


• 
  Laryngospasm – Involuntary contraction of the vocal folds restricting inhalation


• 
  The Last Dive – Non-fiction book by Bernie Chowdhury about a double wreck diving fatality


• 
  Latent hypoxia – Tissue oxygen concentration which is sufficient to support consciousness at depth, but not at surface pressure


• 
  Life support technician – A member of a saturation diving team who operates the surface habitat


• 
  Lifting bag – Airtight bag used for underwater buoyant lifting when filled with air


• 
  Limpet mine – A type of naval mine which is attached to a target by magnets


• 
  Line marker – Marker used on cave guide lines to provide safety information to divers


• 
  Lipid – A substance of biological origin that is soluble in nonpolar solvents


• 
  List of diver certification organizations – Agencies which issue certification for competence in diving skills


• 
  List of diving hazards and precautions – List of the hazards to which an underwater diver may be exposed, their possible consequences and the common ways to manage the associated risk


• 
  List of legislation regulating underwater diving – List of national and state legislation regulating underwater diving


• List of military diving units


• 
  List of signs and symptoms of diving disorders – The signs and symptoms of physiological disorders resulting from underwater diving


• 
  List of United States Navy SEALs – Notable current and former members of the United States Navy SEALs and Underwater Demolition Teams


• 
  Liveaboard – Way of using a boat


• 
  Lockout-tagout (LOTO) – A safety procedure to isolate dangerous equipment and render it inoperative during maintenance or repair work


• 
  Longshore current – A current parallel to the shoreline caused by waves approaching at an angle to the shoreline

M[edit]

• 
  Marine Commandos – Special operations group of the Lebanese Navy


• 
  Master diver (United States Navy) – Senior diver rating in US Navy


• 
  Master Instructor – A certificate given in recognition of a minimum level of experience in training divers after certification as a Diving Instructor, issued by PADI and SSI


• 
  Master Scuba Diver – The highest non-leadership recreational scuba diver certification issued by some agencies


• 
  Maximum operating depth – Depth of seawater at which a specified breathing gas mixture will have a limiting maximum oxygen partial pressure


• 
  Maya AUV India – Autonomous underwater vehicle from National Institute of Oceanography, India


• 
  Media diving – Underwater diving in support of the media industries


• 
  Medical fitness to dive – The medical fitness of a person to function safely underwater under pressure


• 
  Membrane method of gas concentration – A method of producing nitrox by passing air though a selectively permeable membrane to reduce nitrogen fraction


• 
  Metabolism – The set of life-sustaining chemical transformations within the cells of organisms


• 
  Metre sea water – Unit of pressure equal to one tenth of a bar


• 
  Military diving – Underwater diving in a military context by members of an armed force


• 
  Minedykkerkommandoen – Norwegian Navy clearance diver unit


• 
  Minentaucher – Mine clearance divers of the German Navy


• 
  Mitchell, Simon – New Zealand physician and author on diving medicine


• 
  Mk 1 Underwater Defense Gun – Underwater firearm developed by the United States during the Cold War


• 
  Molecular diffusion – The thermal motion of liquid or gas particles at temperatures above absolute zero


• 
  Momsen, Charles – American pioneer in submarine rescue for the United States Navy


• 
  Monofin – Single blade swimfin attached to both feet


• 
  Moon pool – An opening in the base of a hull, platform, or chamber giving access to the water below


• 
  Motorised Submersible Canoe – WWII British frogman delivery vehicle


• 
  Muck diving – Recreational diving on a loose sedimentary bottom

N[edit]

• 
  National Academy of Scuba Educators (NASE) – Recreational scuba training and certification agency


• 
  National Association for Cave Diving (NACD) – American non-profit organization for improving cave diving safety


• 
  National Association of Underwater Instructors (NAUI) – A non-profit training and certification agency association of scuba instructors


• 
  National Board of Diving and Hyperbaric Medical Technology – A non-profit organization for education and certification in diving and hyperbaric medicine


• 
  National Navy UDT-SEAL Museum – Museum recording the history of US Navy UDT and SEAL teams and their members


• 
  National Oceanic and Atmospheric Administration (NOAA) – An American scientific agency within the US Department of Commerce that focuses on the oceans and the atmosphere


• 
  National Speleological Society Cave diving section – Organization for exploration, conservation, and study of caves in the United States


• 
  Nautical Archaeology Society (NAS) – British organisation to further research in nautical archaeology for the public benefit


• 
  Naval Air Command Sub Aqua Club – An organisation within the Royal Navy for recreational and technical diving training for British naval aviation and fleet units


• 
  Naval Service Diving Section – Diving unit of the Irish Naval Service


• 
  Naval Submarine Medical Research Laboratory – Research unit for submarine and diving medicine


• 
  Navy diver (United States Navy) – Personnel in the United States Navy who are qualified in underwater diving and salvage


• 
  Necker Nymph – A DeepFlight Merlin class positively-buoyant open-cockpit 3-seater wet sub


• 
  Nederlandse Onderwatersport Bond (NOB) – National governing body for recreational diving and underwater sports in the Netherlands affiliated to CMAS


• 
  Nereus (underwater vehicle) – Hybrid remotely operated or autonomous underwater vehicle


• 
  Neutral buoyancy – State of equilibrium between buoyancy and weight of a fully immersed object


• 
  Night diving – Underwater diving during the hours of darkness


• 
  Nitrogen narcosis – Reversible narcotic effects of respiratory nitrogen at elevated partial pressures


• 
  Nitrox – Breathing gas, mixture of nitrogen and oxygen


• 
  Nitrox production – Methods of producing nitrox mixtures


• 
  NOAA Diving Manual – Training and operations manual for scientific diving


• 
  No-limits apnea – Freediving discipline in which the diver descends and ascends using their method of choice


• 
  Nondestructive testing – Evaluating the properties of a material, component or system without causing damage


• 
  Normocapnia – Normal arterial carbon dioxide levels


• 
  Nuclear diving – Diving in an environment where there is a risk of exposure to radioactive materials

O[edit]

• 
  Occupational diving, also known as Professional diving – Underwater diving where divers are paid for their work


• 
  Occupational safety and health, also known as Occupational health and safety – Field concerned with the safety, health, and welfare of people at work


• 
  Ocean current – Directional mass flow of oceanic water generated by external or internal forces


• 
  Open Water Diver – An entry-level autonomous diver certification for recreational scuba diving


• 
  Open-water diving – Diving in unrestricted water and in water when the diver has unrestricted vertical access to the surface


• 
  Operation Algeciras – Failed Argentine plan to sabotage a British warship in Gibraltar during the Falklands War


• 
  Operation Thunderhead – American amphibious mission during the Vietnam War


• 
  Operations manual – authoritative document of how things should be done in an organisation


• 
  Oxygen compatibility – Use of equipment and materials that are suitable for service with a high partial pressure of oxygen


• 
  Oxygen therapy – Use of high inhalation concentrations of oxygen as medical treatment


• 
  Oxygen toxicity – Toxic effects of breathing in oxygen at high concentrations


• 
  Oxygen window in diving decompression – Physiological effect of oxygen metabolism on the total dissolved gas concentration in venous blood

P[edit]

• 
  Partial pressure – Pressure attributed to a component gas in a mixture


• 
  PASKAL – Special operations force of the Royal Malaysian Navy


• 
  Patent foramen ovale – A congenital heart defect in which blood can flow through an opening between the atrial chambers of the heart


• 
  Pearl hunting – Collecting pearls from wild mollusks


• 
  Penetration diving – Diving under a physical barrier to a direct vertical ascent to the surface


• 
  Performance Freediving International (PI) – Freediver training agency


• 
  Perfusion – Passage of fluid through the circulatory or lymphatic system to an organ or tissue


• 
  Permeation – The penetration of a liquid, gas, or vapor through a solid


• 
  Permit To Work – Work safety management system


• 
  Physiological response to water immersion, also known as Diving reflex – The physiological responses to immersion of air-breathing vertebrates


• 
  Physiology of decompression – The physiological basis for decompression theory and practice


• 
  Physiology of underwater diving – Influences of the underwater environment on the physiology of air-breathing animals


• 
  Polespear – Basic rubber launched underwater fishing spear


• 
  Police diving – A branch of professional diving carried out by police services


• 
  Pony bottle – Small independent scuba cylinder usually carried for emergency gas supply


• 
  Porpoise – Australian scuba manufacturer


• 
  Powerhead – Specialized firearm used underwater that is fired when in direct contact with the target


• 
  Pressure – Force distributed perpendicularly over an area


• 
  Pressure swing adsorption – method of gas concentration using selective adsorbtion under pressure


• 
  Psychrometric constant – relation of the partial pressure of water in air to temperature


• 
  Professional Association of Diving Instructors (PADI) – Recreational diver training and certification agency


• 
  Professional diving, also known as Occupational diving – Underwater diving where divers are paid for their work


• 
  Professional Diving Instructors Corporation (PDIC) – Recreational diver training and certification agency


• 
  Public safety diving – Underwater work done by law enforcement, rescue and search and recovery teams


• 
  Pulmonary barotrauma – Lung over-pressure and squeeze injuries


• 
  Pulmonary circulation – The part of the circulatory system which carries blood from heart to lungs and back to the heart


• 
  Pyle stop – A series of short deep decompression stops in addition to the standard profile

R[edit]

• 
  R-2 Mala-class swimmer delivery vehicle – 2-man wet sub swimmer delivery vehicle class of the Yugoslavian, and later, Croatian, Navies


• 
  Raid on Alexandria (1941) – Italian frogman raid on British warships in Alexandria in 1941


• 
  Raid on Algiers – Italian frogman raid on Allied ships in Algiers harbour in 1942


• 
  Rash vest – Stretch garment for protection from abrasion, UV and stings


• 
  Ratio decompression – Rule of thumb for estimating a decompression schedule for a given set of breathing gases


• 
  John Rawlins R.N. – Royal Navy officer and pioneer in the field of diving medicine


• 
  Rebreather – Apparatus to recycle breathing gas


• 
  Rebreather diving – Underwater diving using self contained breathing gas recycling apparatus


• 
  Recreational Dive Planner – A PADI no-decompression dive table also available as a circular slide rule and electronic calculator


• 
  Recreational dive sites – Specific places that recreational divers go to enjoy the underwater environment or are used for training purposes


• 
  Diver certification, also known as Recreational diver certification – Certification as competent to dive to a specified standard


• 
  Recreational diver training – Processes by which people develop the skills and knowledge to dive safely for recreational purposes


• 
  Recreational diving – Diving for the purpose of leisure and enjoyment, usually when using scuba equipment


• 
  Reduced gradient bubble model – An algorithm by Bruce Wienke for modelling inert gases leaving the body during decompression in mixed dissolved and bubble phases


• 
  Redundancy (engineering) – Duplication of critical components to increase reliability of a system


• 
  Reef Life Survey (RLS) – Marine life monitoring programme based in Hobart, Tasmania


• 
  Remotely operated underwater vehicle – A tethered underwater mobile device operated by a remote crew


• 
  REMUS (AUV) – Autonomous underwater vehicle series


• 
  Rescue Diver – Recreational scuba certification emphasising emergency response and diver rescue


• 
  Respiration (physiology) – The movement of oxygen from the outside environment to the cells within tissues, and the removal of carbon dioxide


• 
  Respiratory exchange ratio – The ratio between the amount of carbon dioxide produced in metabolism and oxygen used


• 
  Respiratory quotient – Ratio of carbon dioxide produced by the body to oxygen consumed by the body


• 
  Respiratory system – A biological system of specific organs and structures for gas exchange in animals and plants


• 
  Rip current – Narrow current of water which moves directly away from the shore, cutting through the lines of breaking waves


• 
  Risk assessment – Estimation of risk associated with exposure to a given set of hazards


• Risk control


• 
  Risk management – Set of measures for the systematic identification, analysis, assessment, monitoring and control of risks


• 
  Röjdykare – Clearance divers of the Swedish Navy


• Royal Australian Navy School of Underwater Medicine


• 
  HMS Royal George (1756)#Salvage attempts – 100-gun first-rate Royal Navy ship of the line (1756) – Early salvage operation using bells and surface supplied divers


• 
  Rubicon Foundation – Non-profit organization for promoting research and information access for underwater diving


• 
  Rule of thirds (diving) – Rule of thumb for scuba gas management


• 
  Russian commando frogmen – Tactical scuba diving unit

S[edit]

• 
  Safety culture – The attitude, beliefs, perceptions and values that employees share in relation to risks in the workplace


• 
  Safety data sheet, also known as Material safety data sheet – System for cataloging information, potential hazards and instructions for safe use associated with a material or product


• 
  Salvage diving – The diving work associated with the recovery of vehicles, cargo and structures


• 
  Saturation diving – Diving for periods long enough to bring all tissues into equilibrium with the partial pressures of the inert components of the breathing gas


• 
  Save Ontario Shipwrecks (SOS) – A provincial heritage NGO in Ontario, Canada


• 
  Scientific diving – The use of diving techniques by scientists to study underwater what would normally be studied by scientists on land


• 
  Scottish Sub Aqua Club (ScotSAC) – Scottish recreational diver training and certification agency


• 
  Scuba diving – Diving while breathing from self-contained underwater breathing apparatus


• 
  Scuba diving fatalities – Deaths occurring while scuba diving or as a consequence of scuba diving


• 
  Scuba Diving International (SDI) – Recreational diver training and certification agency


• 
  Scuba Educators International (SEI) – Recreational diver training and certification agency


• 
  Scuba gas planning – Estimation of breathing gas mixtures and quantities required for a planned dive profile


• 
  Scuba manifold – Scuba component used to connect two diving cylinders


• 
  Scuba Schools International (SSI) – Recreational scuba and freediving training and certification agency


• 
  Scuba set – Self contained underwater breathing apparatus


• 
  Scuba skills – The skills required to dive safely using self-contained underwater breathing apparatus


• 
  Sea Research Society – American non-profit educational society


• 
  Sea Trek (diving system) – Recreational underwater diving system using helmets


• 
  SEAL Delivery Vehicle (SDV) – Manned wet submersible for deploying Navy SEALS


• 
  Seasickness, also known as Motion sickness – Nausea caused by motion


• 
  Sentry (AUV) – Autonomous underwater vehicle made by Woods Hole Oceanographic institution


• 
  Shadow Divers – Book by Robert Kurson recounting the discovery of a World War II German U-boat wreck


• 
  Shark tourism – Tourism industry based on viewing live sharks in their natural habitat


• 
  Shayetet 13 – Special operations unit of the Israeli Navy


• 
  Shilling, Charles Wesley – US Navy physician and decompression and hyperbaric medicine researcher


• 
  Ships husbandry diving – Diving related to the maintenance and upkeep of ships


• 
  Sidemount diving – Diving using an equipment configuration where the scuba sets are clipped to the sides of the harness


• 
  Siebe Gorman CDBA – A type of diving rebreather used by the Royal Navy


• 
  Silt out – Reduction of underwater visibility by disturbing silt deposits


• 
  The Silent World: A Story of Undersea Discovery and Adventure – Book by Jacques-Yves Cousteau and Frédéric Dumas


• 
  Siluro San Bartolomeo – Italian manned torpedo design of late WWII


• 
  Single point of failure – A part of a system that, if it fails, will stop the entire system from working


• 
  Sinking of the Rainbow Warrior – Covert attack by French military frogmen on a civilian ship in peacetime


• 
  Siva – Military diving rebreather


• 
  Skandalopetra diving – Freediving using a stone weight at the end of a rope to the surface


• 
  Snell's law, also known as Law of refraction – The relation between the angles of incidence and refraction of waves crossing the interface between isotropic media


• Snoopy loop


• 
  Snorkel represented by Snorkeling#Snorkel – Short curved tube used for face-down breathing at the surface


• 
  Snuba – Limited depth airline breathing apparatus towed by the diver


• 
  Solo diving – Recreational diving without a dive buddy


• 
  Solubility – Capacity of a designated solvent to hold a designated solute in homogeneous solution under specified conditions


• 
  Solution – A homogeneous mixture which assumes the phase of the solvent


• 
  South African Department of Labour – Department of the South African government responsible for matters related to employment


• 
  South African Environmental Observation Network (SAEON) – A network of people, organisations and observation platforms, that perform Long-Term Ecological Research in South Africa and surrounding waters


• 
  South African Underwater Sports Federation (SAUSF) – The official World Underwater Federation representative body in the Republic of South Africa.


• 
  South Pacific Underwater Medicine Society (SPUMS) – A publisher for diving and hyperbaric medicine and physiology


• 
  Southern African Underwater and Hyperbaric Medical Association (SAUHMA) – A special interest group of the Council of the South African Medical Association


• 
  Spearfishing – Hunting for fish using a spear


• 
  Speargun – Underwater fishing implement


• 
  Special Boat Service – Special forces unit of the Royal Navy


• 
  Special Duties Unit – Hong Kong Police tactical unit


• 
  Special Service Group (Navy) – Pakistan Navy special operations unit


• 
  Spindle (vehicle) – Ice penetrating two-stage autonomous underwater vehicle


• 
  SPURV – Self propelled underwater research vehicle built in 1957 for the US Navy


• 
  SPURV II – Special purpose underwater research vessel built to srudy submarine wakes


• 
  Sponge diving – Diving to gather natural sponges


• 
  Sport diving (sport) – Underwater sport using recreational open circuit scuba equipment in a swimming pool


• 
  SPP-1 underwater pistol – Soviet four-barreled underwater dart pistol


• 
  Standard diving dress – Rubberised canvas diving suit with copper helmet and weighted boots


• 
  Standard operating procedure – A set of detailed instructions compiled by an organization to help workers carry out operations safely and effectively


• 
  Stand-by diver – A member of a dive team who is ready to assist or rescue the working diver


• 
  Star Canopus diving accident – Fatal offshore diving bell accident in 1978


• 
  Static apnea – A discipline in which the diver holds their breath underwater for as long as possible, and need not swim any distance


• 
  Stratification – Stable water layers of different properties that act as a barrier to vertical mixing


• 
  Sub-Aqua Association (SAA) – British recreational diver training and certification organisation


• 
  Subsurface (software) – Software for logging and planning recreational dives


• 
  Supersaturation – State of a solution that contains more solute than can be dissolved at equilibrium


• 
  Supervised diver – Minimum requirements for a recreational diver to dive in open water under direct supervision


• 
  Surface marker buoy – A buoy towed a scuba diver to indicate the diver's position


• 
  Surface-supplied diving – Underwater diving breathing gas supplied from the surface


• 
  Surface-supplied diving equipment – Equipment used specifically for surface supplied diving


• 
  Surface-supplied diving skills – Skills and procedures required for the safe operation and use of surface-supplied diving equipment


• 
  Surface tension – Tendency of a liquid surface to shrink to reduce surface area


• 
  Surfactant – Substance that lowers the surface tension between a liquid and another material


• 
  Surfer's ear – The common name for an abnormal bone growth within the external ear canal


• 
  Surge (wave action) – The component of wave motion close to and parallel with the bottom


• 
  Sustained load cracking – Metallurgical failure mode of cracking under a prolonged static load


• 
  Swimfin – Finlike accessories worn on the feet, used for swimming, snorkeling and diving propulsion


• 
  Systemic circulation – The portion of the cardiovascular system which transports oxygenated blood away from the heart (between heart and body cells)

T[edit]

• 
  Taifib – Indonesian amphibious reconnaissance unit


• 
  Taravana – Decompression sickness after breath-hold diving


• 
  Task loading – The relationship between operator capacity and the accumulated activities than must be done


• 
  Technical diving – Extended scope recreational diving


• 
  Technical Diving International (TDI) – Technical diver training and certification agency


• 
  Technical Extended Range (TXR) – Recreational scuba and freediving training and certification agency


• 
  Testing and inspection of diving cylinders – Periodical inspection and testing to revalidate fitness for service


• 
  Thalmann algorithm – Recent US Navy algorithm for modelling of inert gases entering and leaving body tissues as pressure changes


• 
  Thalmann, Edward D. – American hyperbaric medicine specialist and decompression researcher


• 
  Therapeutic recompression – Recompression to reduce symptoms of decompression illness


• 
  Thermocline – A distinct layer in a large body of fluid in which temperature changes more rapidly with depth than it does in the layers above or below


• 
  Thermodynamic model of decompression – Early model in which decompression is controlled by the volume of gas bubbles coming out of solution


• 
  Theseus (AUV) – Large autonomous underwater vehicle for laying fibre optic cable


• Tianjin University Petrel HUG


• 
  Tidal race – A fast-moving tidal flow passing through a constriction, forming waves, eddies and strong currents


• 
  Tide – The periodic change of sea levels caused by the gravitational and inertial effects of the Moon, the Sun and the rotation of the Earth


• 
  Timeline of diving technology – A chronological list of notable events in the history of underwater diving


• 
  Tissue (biology) – An ensemble of similar cells and their matrix with similar origin and function


• 
  Torricellian chamber – An air space in a cave chamber with pressure below atmospheric


• 
  Towboard – Underwater survey equipment used to tow a diver


• 
  Tremie – Equipment for underwater concrete placement


• 
  Triger, Jacques – French geologist who invented the 'Triger process' for digging through waterlogged ground


• 
  Trimix (breathing gas) – Breathing gas consisting of oxygen, helium and nitrogen


• 
  Trimix Scuba Association (TSA) – Recreational technical scuba training and certification agency


• 
  Trongle – Device used on submarines to help swimmers to locate a submerged submarine


• 
  Turbidity – The cloudiness of a fluid caused by large numbers of particles that are generally invisible to the naked eye


• 
  Türkiye Sualtı Sporları Federasyonu (TSSF) – Turkish national governing body for underwater sport and lifesaving

U[edit]

• 
  Uncontrolled decompression – An unplanned drop in the pressure of a sealed system


• 
  Undersea and Hyperbaric Medical Society (UHMS) – US based organisation for research and education in hyperbaric physiology and medicine.


• 
  Undertow (water waves) – Return flow below (nearshore) water waves.


• 
  Underwater archaeology – Archaeological techniques practiced at underwater sites


• 
  Underwater breathing apparatus – Equipment which provides breathing gas to an underwater diver


• 
  Underwater Defence (Turkish Armed Forces) – Special operations unit of the Turkish Navy


• 
  Underwater demolition – The deliberate destruction or neutralization of man-made or natural underwater obstacles


• 
  Underwater Demolition Assault Unit – Special operations force of the Royal Thai Navy


• 
  Underwater Demolition Command – Special warfare unit of the Greek Navy


• 
  Underwater Demolition Team – US Navy special operations group


• 
  Underwater diving – Descending below the surface of the water to interact with the environment


• 
  Underwater diving environment – The underwater environment to which a diver may be exposed


• 
  Underwater firearm – Firearms that can be effectively fired underwater


• 
  Underwater football – Underwater team sport using snorkeling equipment and an American football


• 
  Underwater hockey – Two teams compete to maneuver a puck across the bottom of a swimming pool into the opposing team's goal


• 
  Underwater ice hockey – A variant of ice hockey played upside-down underneath frozen pools or ponds on breath-hold


• 
  Underwater Offence (Turkish Armed Forces) – Special operations unit of the Turkish Navy


• 
  Underwater orienteering – Underwater compass navigation and speed competition on scuba.


• 
  Underwater photography – The process of taking photographs while under water


• 
  Underwater photography (sport) – Competitive underwater digital photography on scuba


• Underwater rifle


• 
  Underwater rugby – Two teams try to score a negatively buoyant ball into the opponents’ goal at the bottom of a swimming pool on breath-hold


• 
  Underwater search and recovery – Locating and recovering underwater objects


• 
  Underwater searches – Techniques for finding underwater targets


• 
  Underwater Society of America (USOA) – American national representative organization for underwater sport.


• 
  Underwater sports – Competitive underwater sports


• 
  Underwater target shooting – Breathhold underwater sport of target shooting with a speargun in a swimming pool.


• 
  Underwater videography – The branch of electronic underwater photography concerned with capturing moving images


• 
  Underwater vision – Effects of the underwater environment on (human) vision


• 
  Underwater warfare – One of the three operational areas of naval warfare


• 
  Unified Team Diving (UTD)


• 
  United Diving Instructors (UDI) – Recreational diver training and certification agency


• United States Marine Corps Combatant Diver Course


• 
  United States military divers – Underwater divers employed by the US armed forces, including navy, army, marines, air force and coast guard


• 
  United States Navy Experimental Diving Unit (NEDU) – The primary source of diving and hyperbaric operational guidance for the US Navy


• 
  United States Navy SEALs – US Navy special operations force


• 
  United States Navy SEAL selection and training – Selection and training procedures and criteria


• 
  Universal Referral Program – A system to complete recreational scuba training with another instructor


• 
  Upwelling – The replacement by deep water moving upwards of surface water driven offshore by wind

V[edit]

• 
  Variable weight apnea – Worldwide rule- and record-keeping body for competitive breath-hold events


• 
  Varying Permeability Model – Decompression model and algorithm based on bubble physics


• 
  Venture One diving accident – Saturation diving fatality in the North Sea in 1977


• 
  Vertigo – Type of dizziness where a person feels as if they or the objects around them are moving


• 
  Vintage scuba – Early model scuba equipment and the ongoing activity of diving with it


• 
  Viper – Electronically-controlled closed circuit mixed gas military rebreather

W[edit]

• 
  Waage Drill II diving accident – Fatal saturation diving accident in the North Sea in 1975


• 
  Water safety – Human safety in the vicinity of bodies of water


• 
  Weight – The force on a mass due to gravity


• 
  Weight belt – A ballasted waist belt worn by a diver


• 
  USS Westchester County (LST-1167) – US Navy tank landing ship built in 1952


• 
  Wet Nellie – Submarine car from James Bond movie


• 
  Wet sub – Ambient pressure diver propulsion vehicle


• 
  Wetsuit – Garment for water activities, providing thermal insulation but not designed to prevent water entering


• 
  Wildrake diving accident – Fatal offshore diving accident in Scotland, 1979


• 
  Woodville Karst Plain Project (WKPP) – A project and organization to map the underwater cave systems of the Woodville Karst Plain


• 
  Work of breathing (WOB) – The energy expended to inhale and exhale a breathing gas


• 
  World Recreational Scuba Training Council (WRSTC) – Council of representatives of national or regional recreational diving councils to develop minimum diver training standards


• 
  Wreck diving – Recreational diving on wrecks

Y[edit]

• 
  YMCA SCUBA Program – Defunct recreational diver training and certification agency.

See also[edit]

• Glossary of underwater diving terminology

References[edit]