The oceans don’t remain still; their water is constantly moving in giant circles known as currents. In the Northern Hemisphere, currents move clockwise, while in the Southern Hemisphere they move counterclockwise. Currents help to moderate temperatures on land in places like the British Isles—which are farther north than the U.S.-Canadian border—by sending warm water from the Caribbean northeast across the Atlantic Ocean to northern Europe. A current known as the Antarctic Circumpolar Current circles the southern continent. The North Atlantic and North Pacific oceans each have a large clockwise current, while the South Atlantic and South Pacific oceans each have a large counterclockwise current.
A NASA image measuring temperatures on the Earth reveals the pattern of ocean currents (photo courtesy NASA, Visible Earth Project).