Reading about Scuba on the internet and come across some acronyms and abbreviations that you're not familiar with? This page should help you keep up with the conversations. This is intended as a beginner primer, so some definitions have been somewhat simplified for ease of understanding.

AGE- Arterial Gas Embolism: A potentially serious scuba diving injury caused by bubbles of gas in the bloodstream

AI- Assistant Instructor

AI- Air Integrated: a dive computer attached to an air supply, which provides a digital readout of remaining tank pressure. Used to supplement or replace a traditional analog pressure gauge.

ANDI- American Nitrox Divers, Inc. N.Y.-based technical certification agency.

AOW- Advanced Open Water (there is some debate over just how "advanced" it is, but that's what it stands for)

ATA- ATmospheres Absolute; 1 ATA is the atmospheric pressure at sea level, and an additional atmosphere worth of pressure is added every 33' of sea water. Atmosphere absolute = 14.7 PSI of pressure.

Bar- Metric unit for measuring pressure. A full scuba tank at 3,000 psi reads approximately 200 bar on a metric gauge.

BC- Buoyancy Compensator [Device, sometimes "BCD"] - if you don't know what this is, get certified for scuba then come back.

BOW- Basic Open Water. Not usually an actual course, but useful to distinguish a certification level below AOW.

BP/W- Backplate and Wing, a style of buoyancy compensator characterized by a rigid backplate (aluminum, steel or delrin) and a separate wing, and a streamlined front

BSAC- British Sub Aqua Club. International certification agency based in the United Kingdom.

BT- Bottom Time

BWRAF - PADI training acronym; "Begin with Review and Friend"
(aka "Big White Rabbits are Fluffy", "Blonde Women Really are Fun"), Checklist for pre-dive buddy-checks which stands for BC, Weights, Released, Air, Final check

C-card: scuba diving certification card given by a certification agency such as PADI, NAUI, SSI, GUE, etc.

CD- Course Director. Level of instructor certification authorized to conduct instructor training.

CESA- Controlled Emergency Swimming Ascent

DAN- Divers Alert Network. Nonprofit organization that provides emergency and informational advice and assistance for diving injuries, promotes diving-related medical research and education, collects injury statistics, and offers dive safety services to its members and the diving community.

DCI- Decompression Illness; a generic term for pressure-related scuba injuries including AGE and DCS

DCS- Decompression Sickness; the 'bends'

DIN- Deutsches Institut fuer Normung (German Institute for Standardization, like ISO9000 and ANSI), but in relation to scuba, it usually refers to an alternate to the yoke-style connector on a scuba tank

DIR- Do(ing) It Right, a style of diving that mixes a specific gear configuration and a style a team diving

DM- Dive Master (usually, the person running the show on a dive boat, aside from the Captain. In charge of diving operations, primarily concerned with safety.)

DPV- diver propulsion vehicle. Underwater "scooter" that allows a diver to cover an increased distance underwater.

DS- Dry suit.

EANx- Enriched Air Nitrox, sometimes simply "Nitrox". Refers to air with a higher-than-normal level of oxygen. EAN is a subset of nitrox. Nitrox is any mixture of nitrogen and oxygen, while EAN is air with additional oxygen added.

FFW- Feet of Fresh Water (ex: I dove to 25 ffw in a local quarry on my trip to Idaho)

FSW- Feet of Sea Water (ex: I only went down to 25 fsw for my first dive in Hawaii)

GUE- Global Underwater Explorers: A certification agency leading the DIR diving style. Certifies divers for cave and technical divers. Based in Florida.

HID- High Intensity Discharge, a kind of very bright bulb found in some of your better underwater flashlights

Hog- "Hogarthian". An ultra-simplified gear system developed for cave diving (originally) bu Bill "Hogarth" Main. Used as the inspiration of the DIR gear configuration.

HP- High Pressure, usually refers to a scuba tank that can be filled to pressures greater than 3000 psi without exceeding manufacture and DOT allowable limits. Often combined with the fill rating of a tank (measured in cubic feet) to describe a tank and it's capacity, for instance, an HP100 would be a high pressure tank that holds 100cf of gas when filled to it's rated capacity.

Hydro- Hydrostatic test required for scuba cylinders every five years.

IANTD International Association of Nitrox and Technical Divers. Recreational, cave and technical certification agency.

IDC- Instructor Development Course. A class or series of classes designed to advance the knowledge and skill level of divers so they can qualify as scuba instructors.

IP- Intermediate Pressure; the pressure between the first and second stages of a regulator

ITC- Instructor Training Course. Class in which divers advance their knowledge and skill, and qualify as scuba instructors.

L.A. County- Los Angeles County Department of Parks and Recreation, Underwater Unit. The oldest scuba certification organization. Still in operation today!

LDS- Local Dive Shop

LP- Low Pressure, usually refers to a scuba tank that can only be filled to pressures lower than 3000 psi without exceeding manufacture and DOT allowable limits.

MOD- Maximum Operating Depth, maximum safe depth for a specific Nitrox (or air) mix, beyond which risks of Oxygen Toxicity exceed limits generally regarded as safe.

MOF- Mask on Forehead. Just what you think... your mask on your forehead, a practice frowned upon by many. See NMOF.

NACD- National Association for Cave Diving. Trains and certifies cavern and cave divers.

NAUI- National Association of Underwater Instructors. Not-for-profit recreational and technical certification agency based in Florida.

NDL- No Decompression Limit, max time limit at a given depth without having to decompression stops, i.e., normal recreational diving

NMOF- No Mask on Forehead. Just what you think... NOT having your mask on your forehead, to avoid being frowned upon by those who dislike the practice. See MOF.

NSS/CDS- National Speleological Society/Cave Diving Section. Division of the cavers' society that trains and certifies cavern and cave divers.

OCA- Oxygen Clean Air. Regular air (~21% o2, 79% Nitrogen) that has been cleaned sufficiently so it will not contaminate tanks which have been specially cleaned for use with pure oxygen.

OOA- Out of Air

OW- Open Water. The most common designation for the initial scuba certification that results in qualification to dive without supervision.

PADI- Professional Association of Diving Instructors. Recreational certification agency based in California.

PDIC- Professional Diving Instructors Corporation International. Pennsylvania-based certification agency.

PSD- Public Safety Diver

PSI- Pounds per Square Inch, a measurement of pressure. Commonly used to determine how much gas is in a scuba tank of a known volume.

RDP- Recreational Dive Planner, PADI's regular dive tables used to determine NDLs for purposes of dive planning and logging.

RMV- Respiratory Minute Volume: The volume of gas used in one minute at a given depth, calculated based on SAC. See also, SAC.

SAC- Surface Air Consumption [Rate- sometimes SCR], a way to calculate how long your air will last at a given depth (once you know the rate at the surface, it is a simple calculation to determine it at any depth).

SAR- Search and Rescue

SDI- Scuba Diving International. The recreational scuba training and certification arm of TDI.

SI- Surface Interval, the time spent out of the water between dives, be it 5 minutes, 5 years, or anywhere in between

SMB- Surface Marker Buoy, an inflatable tube device used to attract attention at the surface. Sometimes also used as a flotation device during decompression.

SPG- Submersible Pressure Gauge, that round thing you look at to see how much air your tank has left

SSI- Scuba Schools International. Certification agency based in Colorado.

STA- Single Tank Adapter, an optional component in a bp/w system. Backplates are primarily designed for use with double tanks, so to use them with a single tank, either a wing with special stabilizers is needed or an STA. Also makes it faster and simpler to switch configurations between a doubles wing and doubles tank, and a singles wing and single tank.

TDI- Technical Diving International. Certification agency for technical dive training, based in Maine.

VENTID-C- Acronym describing possible symptoms of DCS: Vision Ears Nausea Twitching Irritation Dizziness Convulsions

VIP- Visual Inspection Program. An annual inspection required for scuba tanks.

WAI- Wireless Air Integrated. A computer with a wireless transponder to send pressure information from a small device mounted on the first stage to a separate computer, usually worn on the wrist.

WKPP- Woodsville-Karst Plains Project; cave diving group

YMCA- Young Men's Christian Association. Maintains an international scuba training and certification program, along with many other family-oriented activities.