This paper describes the results of preliminary studies which were conducted at San Diego, California early in 1953, and detailed large scale field tests conducted during the later months of 1953 and the early part of 1954, chiefly near Santa Barbara, California. These studies are part of an investigation to develop an explosive which would overcome some of the disadvantages of black powder, which now is the only explosive permissible for offshore exploration in California. Special instrumentation was developed for recording the pressure‐time curves from underwater explosions. The predominant characteristics of these curves have been related to seismic record quality and the destruction of fishes and other marine life. The experimental studies have shown that non‐lethal explosives are available which will give record quality and operating costs comparable to the conventional dynamites and which are superior to the black powders.