Abstract : A sonar with a short acoustic pulse and high peak power (0.1 to 0.5 ms, 108 db) has been adapted for shallow water bottom penetration by speeding up the pulse rate to 30 cps. Known as the Pinger Probe, it has evolved from the EG and G sonar Pinger for positioning deep-sea cameras and is a device especially designed to show objects submerged in the soft bottom sediments of rivers, harbors, bays and coast lines. It emits a short, relatively powerful acoustic pulse capable of penetrating certain sediments and reflecting from objects or layers of different densities as a return signal. Coupled with a high resolution Alden recorder, it has a detection capability for locating a variety of sediment layering and shallow buried objects. The increased pulse repetition rate provides much improved resolution.