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The lakes of San Salvador Island, Bahamas, occupy sinkholes and curvilinear depressions between dune ridges. Most lakes have maximum water depths of 2 m. They lie approximately at sea level and are saline to varying degrees. Sea water from the surrounding ocean infiltrates the lake basins through permeable carbonate bedrock. The average salinity of lake waters is controlled by the degree of development of the conduit system, the size of the basin, its elevation relative to sea level, rainfall, and the presence of local freshwater lenses.Ostracodes, which are abundant in these lakes, define three salinity-controlled assemblages: freshwater, marine, and euryhaline. The euryhaline assemblage, consisting of four species, predominates, with a salinity range of 10 to almost 100 ppt.Lake basins typically contain as much as 2 m of unconsolidated Holocene sediment resting on Pleistocene carbonate bedrock. Where different assemblages are present, varying ostracode abundances can be used to subdivide cores into zones. Longer cores exhibit four zones, which are apparently correlative from lake to lake. Consistent ostracode assemblages indicate prevailing or typical salinities in these zones. Different lakes reveal parallel salinity histories. Salinity fluctuations through time are likely to have been caused by changing climate or sea level.Initial study of salinity-controlled Mg concentrations in the carapace of Cyprideis americana gives estimates of salinity similar to those interpreted from assemblages of ostracodes. Salinity minima, which occur at zone boundaries, correlate with Holocene low stands of sea level. In lakes where only the euryhaline assemblage is present, salinity minima may be used for correlation.