The volume of Caribbean Sea water in bivariate classes of potential temperature vs. salinity has been estimated from 76 hydrographic stations. The resulting statistics are presented on a pair of characteristic diagrams. The outstanding feature of the diagrams is the strong mode; nearly half of all Caribbean water lies within o. 1°C and 0.02 per mil of the mode, at 3.9°C, 34.98 per mil. An envelope of all samples has been determined. The waters below 2000 m in each of the four large basins are compared by using only data from a single CRAWFORD cruise. In each basin the deep water is remarkably homogeneous, but the deep waters are different in the eastern (Yucatan and Cayman) and western (Colombia and Venezuela) basins. There appears to be no inflow of deep water through Jungfern Passage, the deepest connection with the Atlantic Ocean, but there may be sporadic inflow through Windward Passage into the western basins. There appears to be no inflow of water at middepth above either sill.