Ever wondered what all those diving ancronyms, slang and jargon mean? Well Indepths has the answer

A type of connection between a regulator first stage and the cylinder. It is shaped like an A, hence the name, and fixes with a yolk screw.

Same as a DSMB, except the unit is fitted with a small air cylinder that allows inflation without the need to use  the divers primary breathing gas source. Specifically used by rebreather divers.

Different names for essentially the same thing. BCD stands for Buoyancy Compensation Device. It is the jacket divers wear to gain neutral buoyancy. Stab or stabiliser jacket comes from a particular BCD made by Scubapro and was one of the forerunners to modern BCDs.

A slang name for decompression sickness.

The front of a boat

The British Sub Aqua Club

Another name for a hyperbaric chamber

A condition suffered by divers when nitrogen bubbles form in the blood and become trapped thus forming a blockage. This, of course, has serious medical implications and it is a condition all divers fear.

Another type of regulator/cylinder connector. This type is a screw-threaded and favoured by the Europeans and technical divers.

the area of a boat where the diving equipment is stored and where divers kit up.

This stands for Diver Propulsion Vehicle. These come in many forms from units that strap to a dive tank to torpedo shaped devices that a diver holds on to

As its name implies a drysuit keeps the user dry while wearing it. The suit is made up of a waterproof material – either neoprene or a tri-laminate – with integral boots and watertight wrist and neck seals. A large waterproof zip allows you to get into and out of the suit.

Delayed Surface Marker Buoy. It has the same purpose as an SMB only they are deployed at the end of the dive. This is the most common type of marker buoy used these days.

A slang word for refilling the gas in a dive cylinder.

A term no underwater photographer wants to encounter as it means water is on the wrong side of their housing.

A boat's kitchen

A toilet on a ship

A hard case used to take a camera underwater. There are housings for both compact style and SLR cameras.

A large metal chamber than can be put under pressure and is used in the treatment of decompression sickness victims among other things.

National Association of Underwater Instructors

The name given to a mixture of nitrogen and oxygen. Air is in fact a form of nitrox, but it generally means a mix of gas with a higher percentage of oxygen.

Found all over scuba equipment. O-rings are made of rubber and keep water out.

this is the name given to a standard regulator and dive cylinder. The open circuit refers to the fact the exhaled gas is released into the water.

The Professional Association of Diving Instructors

A large hook connected to a strong rope which connects to a diver's BCD. This allows him/her to remain stationary in a current while not damaging any coral or fingers.

A shortening of the word regulator. A regulator is a two stage device used to lower the pressure of breathing gas in a dive cylinder to ambient pressure so a diver can breathe easily while underwater.

A Rigid Inflatable Boat. A small – between 5 and 8 metres long generally – solid hulled boat with inflatable rubber tubes around the sides. They make stable platforms and are ideal for diving.

A type of SCUBA unit that reuses the diver's exhaled breath. It takes out the excess carbon dioxide and replenishes the oxygen. There are two types a semi closed which constantly flows gas into the breathing loop and Fully closed, which is controlled by a computer system.

Self Contained Underwater Breathing Apparatus. Basically it's your commonal garden regulator and dive cylinder. Add the two together and you have a scuba unit.

The back of a boat – usually where the dive deck is located

Surface Marker Buoy. An inflatable buoy used to indicate where divers are.

Scuba Instructors

Used by technical and cave divers. Side slungs are cylinders full of different gas mixtures for different parts of a dive.

A one day underwater photographic competition.

The distance you can see underwater – as in visibility