During October 1976, reverberation measurements using wide‐band bionic signals were made in shallow coastal waters (30 m) off Oahu, Hawaii. These measurements were made to help assess the acoustical environment in which porpoises are known to perform effectively. The areas of these experiments were selected to provide a range of bottom types which included sandy, rocky, and a combination of the two. The projector and receiver bandwidths and wide‐band transmitted signal permitted the estimation of bottom backscattering strength over a range of grazing angles (5–40°) and frequencies (20–80 kHz). [Work supported by Naval Sea Systems Command.]