Low-density piezoelectric polymer hydrophones were designed for towed arrays where weight is important. Flexural mode designs consisted of two strips of polymer glued to air-backed rectangular flexural plates made of plastic or metal capable of hydrostatic pressures to 4 MPa. They had sensitivities of −200 dB//1V/μPa and capacitance values of 1000 pF. Another design consisted of double layers of polymer wrapped in three separate sections around a thick-walled, air-filled, plastic cylinder capable of hydrostatic pressures to 12.4 MPa and was positively buoyant. The sensitivity was −212 dB//1V/μPa and the capacitance was 13 000 pF. A final design used the hydrostatic coupling mode and should have great pressure capability. It consisted of 32 layers of polymer, electrically connected in series, and held together by a tight-fitting, oil-filled, polyurethane boot. This hydrophone is semiflexible. The sensitivity was −203 dB//1V/μPa and the capacitance was 350 pF. Details of the designs are discussed and sensitivity variations with pressure and temperature are presented. [Work supported by NAVMAT and NAVELEX.]