Abstract: This invention is a thermoacoustic system for communicating between an airborne or spaceborne vehicle and a sound detector that is located aboard an object beneath the surface of the water. The foregoing system comprises a laser or particle accelerator that is located aboard an airborne or spaceborne vehicle. The laser produces a light beam whose amplitude is subsequently modulated or whose pulses are varied in time. A particle accelerator would produce a pulsed particle beam that varies in time. These modulated or varied pulses are focused or deflected to a small layer of water at the air/water interface so that the beam will be absorbed by the water causing the water to produce an acoustic signal that will propagate to the sound detector.