The Woods Hole Ocean Bottom Hydrophone instrument records the digitized output of a single hydrophone sensor at rates between 250 and 1200 samples per second with a dynamic range of 98 dB and can be deployed at depths to 600 meters. The unit's 200 megabyte disk recorder allows operation for periods up to 5 days. Designed for typical marine seismic refraction operations the unit is reliable and simple to deploy and recover. A detailed description is provided of the instrument design and application including transfer function, clock accuracy, data format, sample data and power requirements.