Measurements of salinity, temperature, and ground-water discharges within the Great Bahama Bank provide evidence of active circulation of near-normal ocean water beneath North Andros Island. Elevated-salinity waters (38‰-42‰) derived by density refulx from the Great Bahama Bank flow eastward beneath the island and mix with normal-salinity cold ground waters (19-20 °C) from deeper than 250 m in the adjacent oceans. East to west flow of water from the Straits of Florida may be driven by head differences generated by the Florida Current, which impinges on the western margins of the platform. Alternatively, density differences between the reflux and Tongue of the Ocean sea waters may cause more local circulation on the eastern flanks. These flows have important diagenetic implications, particularly in the explanation of pervasive secondary dolomitization widely reported at shallow depths in the Bahamas.