Here’s your guide of scuba terminology in alphabetical order, ranging from technical terms to slang.
Actual Bottom Time (ABT)
In repetitive diving, the total time actually spent under water (in minutes) from the beginning of descent until leaving the bottom for a direct continuous ascent to the surface or safety stop.
Air Compressor
A machine that compresses or pressurises air to fill your cylinders before going diving.
Air Pressure
The force per unit area exerted by the weight of air.
Annual The required yearly visual inspection and check-up for scuba tanks and regulators
Aqua-lung
Underwater breathing equipment consisting of a diving cylinder and diving regulator.
Ascent Rate
The proper speed for ascending, which is no faster than 18 metres/60 feet per minute. A rate slower is acceptable and appropriate.
Bar
Short for barometric pressure. The method of measurement of air pressure used throughout most of the world and by the compressed gas industry – also a place where divers meet after a long hard day of diving.
BC Buoyancy compensator, also known as known as a BCD or buoyancy control device.
Booties Footwear for divers.
Bottom Time
The time from the beginning of descent until the beginning of a direct, continuous ascent to the surface or safety stop.
Buddy
Your diving partner. Very valuable in times of trouble. A good buddy makes diving a lot more enjoyable.
Buoyancy
Upward force exerted by a fluid on any body immersed in it. Buoyant force can be explained in terms of Archimedes’ principle. Scuba divers with good buoyancy control are able to stay neutrally buoyant at any required depth.
Console A unit attached to a hose from the regulator first stage for holding and displaying instruments, including dive computer, depth gauge and compass.
Compressor
A machine used to increase the volume of usable air in a diving cylinder by raising its pressure.
Cylinder
A cylindrical metal container used to safely store high pressure air. Most are made of steel or aluminum. Cylinders came in a variety of air capacities depending upon their pressure rating and size.
Decompression Diving
Diving that requires planning stops during ascent to avoid decompression sickness. In recreational diving (no decompression diving), a decompression stop is considered an emergency proceedure only and is never an intentional part of the dive plan.
Descent/Ascent Line
A line from a boat or buoy which can be used by divers to control their descent or ascent.
Diaphragm Regulator
A diaphragm first-stage design inherently prevents water from entering the first-stage mechanism itself. This helps to prevent internal corrosion and contamination buildup, which may lead to more consistent performance between service intervals.
Dive Computer
Device that does all the had work for you. No more multi level diving calculations, no more PADI wheel.
Dry Suit
A diving suit designed to thermally insulate and provide protection to the skin of the diver.
Enriched Air Nitrox
This is one of the naming conventions for a non-normal mixture of oxygen and nitrogen.
Farmer john wetsuit pants that extend over the upper body and shoulders, simular to gardener’s overalls).
Fins
Worn on the feet to increase maneuverability and allow for faster swimming. A great point of discussion between divers – who has the fastest and most efficient fins.
First Stage
The part of the regulator which attaches to the scuba tank valve and which is responsible for the first level of tank pressure reduction.
Full Foot Fins
These diving fins are predominantly used for snorkelling and warm water diving. They comprise of a rubber sock like unit to keep the fins on your feet.
Gauge
Any instrument used to measure or quantify, typically used to measure cylinder pressure, depth and direction in diving.
Lead The weights worn to offset a diver’s positive buoyancy.
Lift Bag
Like underwater balloons. Helps lifting heavy objects underwater using bags filled with air at depth.
Live Aboard
Dive boat with sleeping and eating facilities
Log Book
List of the dives a diver has recorded for proof of experience.
Mil Short for millimeter, usually used in reference to wetsuit thickness (i.e., a three-mil suit).
Nitrox
A breathing gas consisting of oxygen and nitrogen
No Decompression Limit
The maximum time that can be spent at a depth before decompression stops are required. Also called “no-stop time”.
Octopus – Occy
Extra second stage regulator alternate air source used by your buddy in an out of air emergency. Also referred to as an Occy.
Open Heel Fin
Type of fin used mainly with drysuits, and where boots are worn, open back to slot foot in, with strap to keep them on your feet.
O-ring A pliable ring that forms a high-pressure seal on tank valves; also used on underwater cameras and other equipment to provide a waterproof seal.
Port An opening in the regulator first stage for hose attachment.
Primary The main regulator second stage, as opposed to the backup or octopus second stage.
Regulator – Reg
Regulators reduce the highly compressed tank pressure to ambient pressure for easy breathing pleasure. A regulator set is typically sold as a first stage regulator, plus a second stage regulator. Most divers then add a reserve 2nd stage regulator, also called occy or octopus.
Second stage The part of the regulator at the end of the hose that includes the mouthpiece. The second stage reduces the pressure in the hose to a breathable pressure.
Semi-dry Suit
A wet suit with wrist and ankle seals to reduce entry and exit of water.
Shorty A one-piece wetsuit with short legs and short sleeves.
Snorkel
Breathing device consisting of a bent tube fitting into a swimmer’s mouth and extending above the surface. Allows swimmer to breathe while face down in the water.
Surface Interval
The time on the surface between dives. Divers need to track this time interval for planning decompression for the next dive
Time To Fly
Divers must wait approx. 24 hours after the last dive before flying to reduce the risk of decompression sickness.
Wall Diving
Diving along the face of a vertical wall – requires good buoyancy control because there is no seabed to prevent the diver descending too deep.
Weight Belt
A heavy belt worn around the waist to help a diver descend, and stop them rising to the surface involuntarily. Usually contains a set of lead weights.
Wet Suit
A tightly fitting neoprene thermally-insulating diving suit that allows a limited volume of water inside the suit.
