Abstract: A small, portable lightweight, water-resistant, manually-operated signalling device. The signalling device includes a signalling assembly fully enclosed within a pair of hermetically sealed housings. The signalling assembly includes a signalling circuit and a pressure sensitive switch adapted, when depressed, to actuate the signalling circuit. One of the housings includes a recessed, flat, semi-rigid deflective wall having an indentation formed therein and in physical contact with the pressure sensitive switch. The indentation is capable of being manually depressed and, when depressed, to transmit the pressure applied to the indentation to the switch, thereby operating the signalling circuit. The indentation and the switch are arranged with respect to each other so that depression of the switch and actuation of the signalling circuit can only occur in response to pressure being applied to the indentation.