Index of underwater diving

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

• 1982 invasion of the Falkland Islands – 1982 Argentine invasion of the Falklands
• 2013 Finswimming World Championships – International competition in Kazan, Russia
• 2016 Finswimming World Championships – International competition in Volos, Greece
• 2018 Finswimming World Championships – International competition in Belgrade, Serbia

A

• 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 – 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) – American diving standards organisation
• American Canadian Underwater Certifications (ACUC) – Recreational diver training and certification agency
• American Nitrox Divers International (ANDI) – Recreational diver training and certification agency
• Amontons' law – Relationship between pressure and temperature of a gas at constant volume.
• Anti-fog – Chemicals that prevent the condensation of water as small droplets on a surface
• Anti-frogman techniques
• Apnea finswimming – Underwater swimming in a swimming pool using mask, monofin and holding one's breath.
• APS underwater rifle – Soviet underwater assault firearm 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 – Armed forces occupation
• 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) – 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 – Unmanned underwater vehicle in development in by Central Mechanical Engineering Research Institute
• AUV Abyss – 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

• Bachrach, Arthur J. – American psychologist and administrator (1923–2011)
• 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 – British autonomous underwater vehicle, named by an online poll
• 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 – 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 function of breathing regulators
• British commando frogmen – Special Boat Service, whose members are drawn largely from the Royal Marines
• 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 – Mathematical model of tissue inert gas uptake and release with pressure change
• Built-in breathing system (BIBS) – System for supply of breathing gas on demand within a confined space
• Buoyancy – Upward force that opposes the weight of an object immersed in fluid
• Buoyancy compensator (BCD), also known as Buoyancy control device – Equipment for controlling the buoyancy of a diver
• Burst disc, also known as rupture disc – Non-closing over-pressure relief device
• Byford Dolphin#Diving bell accident – Explosive decompression of saturation system on semi-submersible offshore drilling rig

C

• 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 – 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 – Aide-memoire to ensure consistency and completeness in carrying out a task
• Christ of the Abyss – Submerged statue of Jesus Christ
• 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
• Code of practice – 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 – Combination of Charles', Boyle's and Gay-Lussac's gas laws
• Comhairle Fo-Thuinn (CFT) – Governing body for recreational diving and underwater hockey in Ireland
• Commandos Marine – Special operations forces of the French Navy
• Commercial diver training – Underwater diving where divers are trained for their work
• 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
• 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
• Controlled buoyant lift – A technique used by scuba divers to raise an incapacitated diver to the surface
• Controlled emergency swimming ascent – 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

D

• Dalton's law – Gas law describing pressure contributions of component gases in a mixture
• The Darkness Beckons – 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) – 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) – Adjusting to pressure changes in ascents
• 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 emerging from solution
• 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 – Movement from high to 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 calculate decompression status in real time
• Dive guide (publication) – Travel guides for recreational diving
• Dive leader – Recreational diving 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 – Powered device for diver mobility and range extension (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 – 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 – Cylinder to supply breathing gas for divers
• 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 – Agents and situations that pose a threat to the underwater diver
• 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 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 controls the pressure of a breathing gas supply for diving
• Diving safety – Risk management 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 – 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 and diving equipment to counteract excess buoyancy
• Doing It Right (scuba diving) (DIR) – Technical diving safety philosophy
• Dräger Dolphin – Semi-closed circuit recreational diving rebreather
• Dräger Ray – Semi-closed circuit diving rebreather
• 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 underneath a liquid
• Dry suit – Watertight clothing that seals the wearer from cold and hazardous liquids
• Duty of care – Legal standard of care in activity
• Dynamic apnea – Freediving disciplines where the diver swims horizontally under water
• Dysbaric osteonecrosis – Ischemic bone disease caused by decompression bubbles
• Dysbarism – Medical conditions resulting from changes of ambient pressure.

E

• 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
• Environmental impact of recreational diving – Effects of scuba diving on the underwater environment
• 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) – Umbrella 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 – 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

• 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 action that tends to maintain or alter 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 – Combat swimmer unit of the French Navy
• Frogman – Tactical scuba diver
• Full face diving mask

G

• 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 – Process by which gases diffuse through a biological membrane
• Gay-Lussac's law – Relationship between pressure and temperature of a gas at constant volume.
• 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

• 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 – Numerical hazard rating using colour coded labels
• Hazmat diving – Underwater diving in a known hazardous materials environment
• Health and Safety Executive (HSE) – United Kingdom government agency
• 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 – 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 – Chronological list of notable events in the history of diving decompression.
• 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 physiology of underwater diving – Influences of the underwater environment on the physiology of human divers
• 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 – 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 at raised ambient pressure
• Hyperbaric stretcher – Portable pressure vessel to transport a person under pressure.
• Hyperbaric treatment schedules – Diving decompression treatment
• Hyperbaric welding – Welding metal at elevated pressure
• Hypercapnia – Abnormally high tissue carbon dioxide levels
• Hypocapnia – State of reduced carbon dioxide in the blood
• Hypothermia – Human body core temperature below 35.0 °C
• Hypoxia (medical) – Medical condition caused by lack of oxygen in the tissues

I

• Ice diving – Underwater diving under ice
• IDA71 – Russian military rebreather for underwater and high altitude use
• Ideal gas law – Equation of the 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) – International standard-setting body
• Interspiro DCSC – Military semi-closed circuit passive addition diving rebreather
• Intervention AUV – Type of autonomous underwater vehicle capable of autonomous interventions
• Introductory diving – Non-certification scuba diving experience
• Investigation of diving accidents – Forensic investigation of underwater diving accidents
• In-water recompression – In-water treatment for decompression sickness
• iRobot Seaglider
• 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

• 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

• 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

• Lambertsen Amphibious Respiratory Unit – Early closed circuit oxygen diving rebreather
• Lambertsen, Christian J. – American environmental and diving medicine specialist
• 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 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 – 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 environments by type – Variety of environments that people may dive in
• 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 links to articles on notable military diving units
• List of signs and symptoms of diving disorders – Evidence of physiological disorders resulting from underwater diving
• List of United States Navy SEALs – Notable members of the US Navy SEALs and UDTs
• Liveaboard – Way of using a boat
• Lockout–tagout (LOTO) – Isolation of dangerous machinery
• Longshore current – A current parallel to the shoreline caused by waves approaching at an angle to the shoreline
• Low impact diving – Scuba diving that has minimal environmental effect

M

• Marine Commandos – Special operations group of the Lebanese Navy
• Master diver (United States Navy) – Senior diver rating in US Navy
• Master Instructor – Person who trains and assesses underwater divers
• 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 gas separation – Technology for splitting specific gases out of mixtures
• Metabolism – Set of life-sustaining chemical transformations within living 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 – 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 – 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

• 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) – Non-profit training and certification agency association of scuba instructors
• National Board of Diving and Hyperbaric Medical Technology – 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) – US government scientific agency
• 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 – 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 Special Warfare Command (Thailand) – Special operations force within the Military of Thailand
• Naval Submarine Medical Research Laboratory – Research unit for submarine and diving medicine
• Navy diver (United States Navy) – US Navy personnel qualified in underwater diving and salvage
• Necker Nymph – 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 – Equilibrium between buoyancy and weight of an 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

• 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 – Entry-level autonomous diver certification for recreational scuba diving
• Open-water diving – Diving in unrestricted water when the diver has unrestricted vertical access to the surface
• Operation Algeciras – Argentine plan to sabotage a British warship in Gibraltar
• 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 oxygen as a medical treatment
• Oxygen toxicity – Toxic effects of breathing in oxygen at high concentrations
• Oxygen window in diving decompression

P

• Partial pressure – Pressure attributed to a component gas in a mixture
• PASKAL – Special operations force of the Royal Malaysian Navy
• Patent foramen ovale – A heart defect present at birth
• Pearl hunting – Collecting pearls from wild molluscs
• 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 – Penetration of a liquid, gas, or vapor through a solid
• Permit To Work
• Petrel HUG
• 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
• Pillar valve represented by Scuba cylinder valve – Valve controlling flow of breathing gas into and out of a scuba cylinder
• 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 over an area
• Pressure swing adsorption – Method of gases separation using selective adsorption 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 – Part of the circulatory system which carries blood from heart to lungs and back to the heart
• Pyle stop – Type of short deep decompression stops in addition to the standard profile

R

• 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
• 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 – Portable apparatus to recycle breathing gas
• Rebreather diving – Underwater diving using self contained breathing gas recycling apparatus
• Recreational Dive Planner – PADI no-decompression dive table also available as a circular slide rule and electronic calculator
• Recreational dive sites – Places that divers go to enjoy the underwater environment
• 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 – 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) – Exchange of carbon dioxide and oxygen between environment and tissues
• Respiratory exchange ratio – Ratio between the metabolic production of carbon dioxide and the uptake of oxygen
• Respiratory quotient – Ratio of carbon dioxide produced by the body to oxygen consumed by the body
• Respiratory system – Biological system in animals and plants for gas exchange
• Rip current – Narrow current of water that 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 – Process in which identified risks are reduced or mitigated
• 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 – Unit based in Sydney, Australia.
• 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

• Safety culture – 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 – Diving work associated with the recovery of vehicles, cargo and structures
• Saturation diving – Diving decompression technique
• Save Ontario Shipwrecks (SOS) – A provincial heritage NGO in Ontario, Canada
• Scientific diving – Use of diving techniques in the pursuit of scientific knowledge
• Scottish Sub Aqua Club (ScotSAC) – Scottish recreational diver training and certification agency
• Scuba cylinder valve – Valve controlling flow of breathing gas into and out of a scuba cylinder
• Scuba diving – Swimming underwater breathing gas carried by the diver
• 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 diving tourism – Industry based on recreational diver travel
• 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 functionally connect 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 a 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 or perceived 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
• Shallow Water Combat Submersible – Manned submersible and a type of swimmer delivery vehicle
• Shark tourism – Tourism industry based on viewing sharks in their natural habitat
• Shayetet 13 – Special operations unit of the Israeli Navy
• Shilling, Charles Wesley – U.S. Navy physician, research, and education
• 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 – 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 whose failure will disrupt the entire system
• Sinking of the Rainbow Warrior – Covert attack by French military frogmen on a civilian ship in peacetime
• Siva
• 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 – Formula for refraction angles
• Snoopy loop – Short circular elastic loop, commonly used to hold objects together
• Snorkel – Short, curved tube for breathing face down at the surface of the water
• Snuba – Limited depth airline breathing apparatus towed by the diver
• Solo diving – Recreational diving without a dive buddy
• Solubility – Capacity of a substance to dissolve in a solvent in a homogeneous way
• Solution – Homogeneous mixture of a solute and a solvent
• South African Department of Employment and Labour – Department of the South African government responsible for matters related to employment
• South African Environmental Observation Network (SAEON) – A network to perform long-term ecological research in South Africa and surrounding waters
• South African Underwater Sports Federation (SAUSF) – Official World Underwater Federation representative body in the Republic of South Africa
• South Pacific Underwater Medicine Society (SPUMS) – Publisher for diving and hyperbaric medicine and physiology
• Southern African Underwater and Hyperbaric Medical Association (SAUHMA) – 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 – British special forces unit of the Royal Navy
• Special Duties Unit – Hong Kong Police tactical unit
• Special Service Group (Navy) – Pakistan Navy special operations force
• 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 – Copper helmet with rubberised canvas diving suit and weighted boots
• Standard operating procedure – Set of detailed instructions to assist in workplace safety
• 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 – Discipline in which the diver holds their breath underwater for as long as possible, and does not need to swim any distance
• Stratification – Layering of water with different properties
• Sub-Aqua Association (SAA) – British recreational diver training and certification organisation
• Subsurface (software)
• 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 – Buoy towed by 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 – 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 – Portion of the cardiovascular system which transports oxygenated blood away from the heart

T

• Taifib – Indonesian amphibious reconnaissance unit
• Taravana – Decompression sickness after breath-hold diving
• Task loading – Relationship between operator capacity and the accumulated activities that 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 – 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 –
• Theseus (AUV) –  –
• Tidal race –  –
• Tide –  –
• Timeline of diving technology –  –
• Tissue (biology) –  –
• Torricellian chamber –  –
• Towboard –  –
• Tremie –  –
• Triger, Jacques –  –
• Trimix (breathing gas) –  –
• Trimix Scuba Association (TSA) –  –
• Trongle –  –
• Turbidity –  –
• Türkiye Sualtı Sporları Federasyonu (TSSF) –  –

U

• Uncontrolled decompression –  –
• Undersea and Hyperbaric Medical Society (UHMS) –  –
• Undertow (water waves) –  –
• Underwater archaeology –  –
• Underwater breathing apparatus –  –
• Underwater Defence (Turkish Armed Forces) –  –
• Underwater demolition –  –
• Underwater Demolition Command –  –
• Underwater Demolition Team –  –
• Underwater diving –  –
• Underwater diving in popular culture –  –
• Underwater diving environment –  –
• Underwater environment –  –
• Underwater firearm –  –
• Underwater football –  –
• Underwater hockey –  –
• Underwater ice hockey –  –
• Underwater Offence (Turkish Armed Forces) –  –
• Underwater orienteering –  –
• Underwater photography –  –
• Underwater photography (sport) –  –
• Underwater rifle –  –
• Underwater rugby –  –
• Underwater search and recovery –  –
• Underwater searches –  –
• Underwater Society of America (USOA) –  –
• Underwater sports –  –
• Underwater target shooting –  –
• Underwater videography –  –
• Underwater vision –  –
• Underwater warfare –  –
• United Diving Instructors (UDI) –  –
• United States Marine Corps Combatant Diver Course –  –
• United States military divers –  –
• US Navy Diving Manual –  –
• United States Navy Experimental Diving Unit (NEDU) –  –
• United States Navy SEALs –  –
• United States Navy SEAL selection and training –  –
• Universal Referral Program –  –
• Upwelling –  –

V

• Variable weight apnea –  –
• Varying Permeability Model –  –
• Venture One diving accident –  –
• Vertigo –  –
• Vintage scuba –  –
• Voyage to the Edge of the World –  –

W

• Waage Drill II diving accident –  –
• Water safety –  –
• Weight –  –
• Weight belt –  –
• USS Westchester County (LST-1167) –  –
• Wet Nellie –  –
• Wet sub –  –
• Wetsuit –  –
• Wildrake diving accident –  –
• Woodville Karst Plain Project (WKPP) –  –
• Work of breathing (WOB) –  –
• World Recreational Scuba Training Council (WRSTC) –  –
• World Without Sun –  –
• Wreck diving –  –

Y

• YMCA SCUBA Program –  –

See also

• Glossary of underwater diving terminology –  –