Abstract: A rescue signalling device includes a waterproof buoyant body having a front end and a rear end and a compartment for accommodating a battery to provide a center of gravity for the body to float in water in a substantially upright neutral position with the front end pointing upwards. The device includes a first light source within the front end for energization by the battery to generate a light rescue signal, and a movement sensitive electrical switch for intermittently turning on and off the light source in response to the body being moved by water, back-and-forth, about the neutral position. The device is a lantern incorporating a second light source for lantern light operation.