Abstract: A brightly colored underwater signaling device having a brightly colored watertight container filled with one or more freely-movable spherical objects. Vigorous displacement of the container causes the spheres to collide with and impact both each other and the inner wall of the container to produce an audible rattling sound with a pitch, timbre and intensity which is easily transmitted through water. The device is preferably constructed of PVC pipe containing a plurality of ball-bearings and connected to a skin diver's diving apparatus with a connecting strap.