Hydroacoustic signals from underwater explosions were documented from analog recordings of 20 widely spaced SOFAR depth hydrophones in the North Pacific for a year. The number of shots per month ranged from 300 in winter to 4000 in summer. Source solutions, of accuracy between 10 and 30 miles, were grouped off the west coast of North America, north of Hawaii, and seaward of the Japanese and Kuril Islands.