Abstract: The emergency underwater notification device disclosed, one of which would be carried by each diver on a team of divers at a dive site, comprises (a) an activator; (b) one or more primary signal emitters, each of which emits a primary notification signal upon activation of the activator, the primary signal emitter comprising one or more of the following: a light source, a hydrophone, a siren, a speaker, or an acoustic transducer; (c) one or more secondary signal emitters, each of the secondary signal emitters emitting a secondary communication signal upon activation of the activator; (d) a receiver capable of receiving communication signals; (e) one or more tertiary signal emitters, each of the tertiary signal emitters to emit a tertiary communication signal upon receipt by the receiver of either a secondary communication signal or a tertiary communication signal from another notification device; and (f) one or more quaternary signal emitters, each of the quaternary signal emitters to emit a quaternary notifi