Abstract: The application describes a hydrostatic release device, suitable for releasing life-saving equipment carried on a ship or aircraft when the ship or aircraft sinks or ditches in the sea. A change in ambient pressure is detected by a pressure sensor which opens a liquid-filled chamber and thereby releases a hydrostatic pressure behind a reciprocable member. This reciprocable member then allows release of a release means. The release means can comprise a link prevented from longitudinal movement by an abutment and normally constrained against lateral movement by the reciprocable member. Thus removal of the reciprocable member away from the link enables transverse movement of the link clear of the fixed abutment. Such an arrangement provides a particularly simple and inexpensive release means.