Adjustable buoyancy lifejacket. The horsecollar style of buoyancy compensator. Rarely used nowadays.

Uses an audio signal to transmit information about a tagged animal as well as data on its depth, the water temperature and amount of light in surrounding water.

An air bubble trapped in a blood vessel. Might occur during too fast an ascent or if breath is held when ascending. The bubble can stop blood getting to body tissues.

American Nitrox Divers International. Specialise in training programs for technical diving and closed circuit rebreather systems.

Injury to the middle ear caused by a rapid change in pressure. May result when ears aren't cleared on a descent.

See Decompression Sickness

A solid ediface built by sea creatures, for example a coral reef.

PV = k, where P is pressure, V is volume and k is a constant. Means that if pressure decreases (such as during an ascent) then the volume of gas increases (assuming temperature is constant). And vice [..]

Diving partner.

Migrating down river to breed in the sea.