The path of North Atlantic Deep Water through the world ocean (The "Great Ocean Conveyor Belt"). Blue indicates deep currents, olive intermediate currents (about 1000 m depth) and orange surface currents.
Water sinks to the ocean floor in the North Atlantic Ocean (the brown circle). It moves southward as North Atlantic Deep Water and joins the Circumpolar Current. Some of it returns to the North Atlantic Ocean as a deep current, the remainder rises to intermediate depth, moves north across the equator, rises further into the upper ocean and returns to the North Atlantic Ocean with the surface currents.