A hydrophone array system comprising a plurality of hydrophones fastened to a cable is deployed beneath the sea in a substantially horizontal straight line. A small powered thruster fastened to one end of the cable urges it in a first direction and this urging is resisted by a member, such as a drogue or an anchored subsurface float, fastened to the other end of the cable. Individual signals from each of the hydrophones are conducted to the surface where they are processed and transmitted by a radio link to a nearby aircraft or surface vessel. Beam forming and analysis is performed aboard the aircraft or surface vessel.