One of the classical oceanographic problems that the World Ocean Circulation Experiment (WOCE) will be able to address concerns the formation mechanisms of the oceans' dominant water masses and their subsequent spread thoughout the world's oceans. The formation sites for water mass end members are often mediterranean (or partly enclosed) seas where distinct water mass property characteristics are efficiently produced because of the relatively small volumes of these seas and because of their restricted communication with the ocean interior. The distributions of individual marginal sea water mass characteristics in ocean interiors have proven to be valuable diagnostics for the general circulation. Despite the variety of water mass formation sites on the globe, there exists a strong commonality in the world ocean water mass characteristics. The relative homogeneity is attributable to the active interchange of waters between the oceans. Such interbasin exchange may be thought of as the global adjustment of the oceans to differential thermohaline forcing.