Abstract: A system of ocean depth sounding from the air which consists in projecting an infrared beam (2) down normal to the ocean surface along a forward travel path to backscatter a signal to a receiver (10) to measure distance to the ocean surface, and simultaneously projecting down a green beam (1) to sweep across the direction of travel to backscatter a series of signals from the ocean bottom over an extended width to a second receiver (11), adjusting the receiver gain from the green signal to achieve optimum ocean bottom measurement and calculating ocean depth from the infrared and green signal differential.