Divers like to see how much air they have remaining and their depth, analogue gauges are used as a back up to modern dive computors.

A depth gauge is a pressure gauge that displays the equivalent depth in water.

Most modern diving depth gauges use a mechanical mechanism and analogue display.

A diver uses a depth gauge with decompression tables and a watch to avoid decompression sickness. A common alternative to the depth gauge, watch and decompression tables is a dive computor.

A depth gauge and an oxygen analyser/oxygen sensor can be used to measure the partial pressure of oxygen of the breathing gas, which is necessary to avoid oxygen toxicity.

Digital depth gauges commonly also show the interval of time that the diver has been submerged and show the diver's rate of ascent and descent, which can be is useful for avoiding barotrauma.