Abstract: An underwater diving assistant device. In one embodiment, the present invention comprises a hand-held unit including a display screen. Messages and drawings are written on the display screen using a passive electromagnetic pen. Markings on the screen can be instantly cleared, stored or transmitted to another, similar device by placing the electromagnetic pen in proximity to a command icon on the screen. The unit includes standard dive computer functions. In one embodiment, the unit includes a digital camera and a vessel locator, and generates audible tones under various circumstances. In one embodiment, a power source of the unit is stored in a container fastened to a diver's weight belt and is connected by a tether to the unit.