A scuba set, originally just scuba, is any breathing apparatus that is entirely carried by an underwater diver and provides the diver with breathing gas at the ambient pressure. Scuba is an anacronym for self-contained underwater breathing apparatus. Although strictly speaking the scuba set is only the diving equipment that is required for providing breathing gas to the diver, general usage includes the harness or rigging by which it is carried and those accessories which are integral parts of the harness and breathing apparatus assembly, such as a jacket or wing style buoyancy compensator and instruments mounted in a combined housing with the pressure gauge. In the looser sense, scuba set has been used to refer to all the diving equipment used by the scuba diver, though this would more commonly and accurately be termed scuba equipment or scuba gear. Scuba is overwhelmingly the most common underwater breathing system used by recreational divers and is also used in professional diving when it provides advantages, usually of mobility and range, over surface-supplied diving systems and is allowed by the relevant legislation and code of practice.
Diving with a recreational open-circuit scuba set
Classic twin-hose Cousteau-type aqualung
A single-hose regulator with 2nd stage, gauges, BC attachment, and dry suit hose mounted on a cylinder
Scuba harness with backplate and back mounted "wing" buoyancy compensator Regulator first stage Cylinder valve Shoulder straps Buoyancy compensator bladder Buoyancy compensator relief and lower manual dump valve DV/Regulator second stages (primary and “octopus”) Console (submersible pressure gauge, depth gauge & compass) Dry-suit inflator hose Backplate Buoyancy compensator inflator hose and inflation valve Buoyancy compensator mouthpiece and manual dump valve
Underwater diving, as a human activity, is the practice of descending below the water's surface to interact with the environment. It is also often referred to as diving, an ambiguous term with several possible meanings, depending on context.
Immersion in water and exposure to high ambient pressure have physiological effects that limit the depths and duration possible in ambient pressure diving. Humans are not physiologically and anatomically well-adapted to the environmental conditions of diving, and various equipment has been developed to extend the depth and duration of human dives, and allow different types of work to be done.
Surface-supplied divers riding a stage to the underwater workplace
Mild barotrauma to a diver caused by mask squeeze
Views through a flat mask, above and below water
Recreational breath-hold divers in basic equipment with floats and catch bags suitable for collecting lobster or shellfish