Shots detonated in the bottom of the Northeast Trough (Gulf of Maine) were monitored at SOFAR-depth hydrophone locations on the Continental Slope off the U.S.A. and off the Antillies. Stations in line with the axis of the Northeast Trough received proportionally more shots than those that were off axis. The direct water arrival was followed by a second one that was due to travel paths down the Northeast Trough and, thence, to the listening stations. Additional late arrivals were due to reflections from seamounts. Energy reflected from seamounts lying off the axis of the Northeast Trough was received proportionally less often the further off axis the mounts were, the greater their summit depth, and the greater their range. Additional seamounts, which were masked by others between them and the shot or station, did not reflect. [This presentation represents results of research sponsored by the Office of Naval Research.]