This paper describes a set of unconventional seismic experiments designed to characterize the subsurface hydrate distribution at Mississippi Canyon Block 798 in the northern Gulf of Mexico. The sea floor at the survey site lies within the hydrate stability zone and heat-flow data indicate that the zone may be 400 m thick. Sediments near the sea floor are characterized by relatively weak seismic reflections. It is possible that the weak reflectivity partially is due to dispersed distribution of hydrates within the fine-grained sediments. The data were acquired using a vertical hydrophone array deployed at the sea bottom. Two different approaches were used at the site; one used a conventional seismic source, and the other used the noise generated by the ship. The results from the experiments indicate that the vertical array performs well for high-resolution characterization of the gas-hydrate stability zone.