Thermohaline circulation, also called Global Ocean Conveyor or Great Ocean Conveyor Belt, the component of general oceanic circulation controlled by horizontal differences in temperature and salinity.

The thermohaline circulation, often referred to as the ocean's "conveyor belt", links major surface and deep water currents in the Atlantic, Indian, Pacific, and Southern Oceans. Multiple mechanisms conspire to increase the density of surface waters at high latitudes. Cold winds blowing over the oceans chill the waters beneath them.

The basic thermohaline circulation is one of sinking of cold water in the polar regions, chiefly in the northern North Atlantic and near Antarctica. These dense water masses spread into the full extent of the ocean and gradually upwell to feed a slow return flow to the sinking regions.