Recent reconnaissance of the Blake Ridge Diapir using the submersible Alvin resulted in mapping and sampling of dense invertebrate communities associated with the subsurface methane hydrates. The geographic location of the Blake Ridge methane seeps raises questions about the biogeographical affinities of its fauna. The closest known, deep seep sites are those of the Barbados region to the southeast and of the Florida Escarpment, on the opposite side of the Florida. A primary objective of the field program was to obtain quantitative samples that will allow us to make robust comparisons of species lists among these seep sites to determine the degree of endemicity of their faunas and thus to provide a preliminary assessment of their sensitivity to habitat degradation.