Abstract: A water craft including an inflatable buoyancy chamber, by inflation and deflation of the buoyancy chamber the buoyancy of the craft, floating or submerged, can be regulated. The water craft includes a buoyancy control apparatus for controlling inflation and deflation of the buoyancy chamber via air supplied by a source of compressed gas. The buoyancy control apparatus includes an operator actuable control which sends control signals to a venting device, to a descent device, to an ascent device or to a hovering device.