Diving Glossary
Diving, like any sport that involves a fair amount of equipment, can often be a little confusing due to the sheer volume of acronyms and seemingly alien terms flying around. On this page we try to provide a list of the key terms used in diving to help demystify them! This list is in no way comprehensive (let us know if we have missed anything!) but it's a start. Click on each term to learn more about what it means.
Diving at a location where the water surface is more than about 300 m (980 ft) above sea level, and which requires special dive tables or dive computers to calculate allowed depths and times for safety.
A low-lying coral island, often with wonderful white sand.
A large reef system, normally some miles from the shore, forming a ‘barrier’ at sea level and protecting the coastline from the open sea.
Buoyancy Control Device – a jacket worn by divers to adjust their buoyancy through inflation and deflation.
A free-standing coral ‘hill’ that rises from the sea bed but does not form part of a reef.
Two divers sharing the same demand valve, generally after an out-of-gas emergency.
A procedure carried out by scuba divers using the buddy system where each diver checks that the other's diving equipment is configured and functioning correctly just before the start of the dive.
The use of the buddy system by scuba divers and is a set of safety procedures that improve divers' chances of avoiding or surviving accidents in or underwater by diving in a group of two or three divers.
The ability of a diver to control his or her depth – an essential practical skill in diving.
A machine used to increase the volume of usable air in a diving cylinder by raising its pressure.
Divers Alert Network is a non-profit organisation dedicated to the safety and health of recreational scuba divers. DAN medical insurance is a very cost-effective way of ensuring full medical back-up in the event of a diving accident. Highly recommended.
A potentially lethal diving disorder caused by bubbles of inert gases, such as nitrogen or helium, coming out of solution and becoming trapped in the tissues, organs and blood vessels of the body causing symptoms ranging from rashes to death. Also commonly referred to as DCS.
A wrist or console-mounted guage that monitors all elements of your dive and indicates your nitrogen absorption and when you must move to shallower waters – an important tool in avoiding decompression sickness.
A form of hand sign system used by scuba divers to communicate when underwater.
A dive where the boat follows you as you ‘drift’ along in one direction with the current, as opposed to swimming in one direction and then reversing course to return to a moored boat.
A diving suit designed to thermally insulate and provide protection to the skin of the diver.
A small ‘cruise’ boat, normally providing cabins for around 25 passengers, which takes you to the more distant and inaccessible reefs and becomes a floating hotel to dive from.
List of the dives a diver has recorded for proof of experience.
Unsurprisingly, a dive at night - many underwater animals are nocturnal or behave differently at night.
A condition caused by breathing nitrogen at high pressure and at depth. It feels like being drunk but goes away when you ascend.
As opposed to compressed air normally breathed, nitrox is a blend of gases richer in oxygen and with less nitrogen, enabling longer dives at certain depths. To dive using nitrox you need to be qualified in its use.
The first qualification needed to become a certified diver under the PADI system.
Marine life of the open ocean, such as sharks and manta rays, rather than reef dwelling species.
Equipment that enables you to dive without producing bubbles or sound; consequently, marine life treats you as one of them. Specialist training (and a lot of money – they are expensive pieces of kit!) is required.
A pressure vessel used to treat divers suffering from certain diving disorders such as decompression sickness.
A hook on a cord which you clip onto dead reef to enable you to float in one position in a current.
If you are a qualified diver but have not dived for some time, this simple course will remind you of the basics.
The mouthpiece through which you breath and which regulates the supply of air.
A short course to introduce you to the world of scuba and enable you to enjoy the thrill without having to be qualified. Depth and conditions limited.
Rigid Inflatable Boat – a boat with a rigid hull surrounded by a large Zodiac-like rubber tube.
Self-Contained Underwater Breathing Apparatus, originally invented by Jacques Cousteau and Emile Gagnan in 1942, by cannibalizing a demand valve from a WWII gas-powered Citroën.
Scuba diving that starts from the shore line. As opposed to boat diving which is from a boat.
Surface marker buoy, a small inflated buoy that divers tow when underwater on drift dives to indicate their location to their boat.
A very gentle encounter where the animal is happy to interact with humans on its own terms.
The time between dives. Divers need to track this time interval for planning decompression for the next dive.
A form of scuba diving that exceeds the scope of recreational diving allowing deeper and longer dives.
As opposed to floating over coral or a sandy bottom, here you have the thrill of diving off ‘the wall’. This will be on one shoulder and is normally an almost vertical drop into deep blue. Here you have the best chance of seeing larger pelagic life. Many of the best dives are wall dives as you fly along over the abyss, a fabulous experience.
