Pronounced salt concentration gradients in five Antarctic, Arctic, and Pacific coastal lakes can be accounted for by diffusional transport of salt out of the deeper saline water layers. The Antarctic lakes studied are Lakes Bonney and Vanda. The computed values of the mean salt diffusion Coefficients based on the ages of salinity stratification, agree to within an order of magnitude with molecular diffusivites for four out of five lakes. This agreement suggests that no major mixing events occurred in the water column during the late historical stages of the lakes. Upper limit time estimates for the removal of most of the salt from the saline bottom layers range rom 5000 to 35000 years, depending on lake depth.