Piezoelectric polyvinylidene fluoride (PVF2) film has been successfully used as the transduction material in the construction of a practical hydrophone, thus demonstrating the feasibility of using this material in underwater acoustics. The PVF2 film is mounted on a flexing circular plate (disk) for strength under hydrostatic pressure; strains developed on the disk surface by incident acoustic pressure are exploited to excite the PVF2. An analytic expression has been developed to find the free-field voltage sensitivity of the hydrophone when the disk boundary is simply supported, and the sensitivity of a carefully constructed prototype was measured for experimental verification. Additional hydrophones were constructed to produce better sensitivity and were tested under a wider range of temperatures and pressures. Hydrophones constructed to withstand pressures up to 4 MPa typically exhibited sensitivities of −200 dB//1 V/μPa and were neutrally buoyant in water.