A two-way communication device includes a central processing unit, a power source in electrical communication with the central processing unit, and a transmitter/receiver unit capable of transmitting and receiving electromagnetic signals. The transmitter/receiver unit is also in electrical communication with the central processing unit. A display, connected to the central processing unit, is capable of displaying messages. A key pad, also in electrical communication with the central processing unit, has a plurality of keys, each of which are capable of generating a specific message. An emergency detecting component, in electrical communication with the central processing unit, is capable of detecting a specific emergency and relating information about the emergency to the central processing unit. The arrangement is such that upon such detection of an emergency by the emergency detecting component, the transmitter/receiver unit transmits a message about the emergency on the display of another identically constructed device.

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.