Illustration showing global ocean currents. Cold deep ocean currents are blue. Warm surface currents are red. Surface currents are driven by the winds, deep ocean currents are driven by density differences due to temperature and salinity. Around the Antarctic is the eastward flowing Antarctic Circumpolar current. It is unobstructed by land for the entire circuit of the Earth and is the strongest current. The Gulf Stream arises in the Caribbean Sea and travels up the Eastern coast of the USA before crossing the Atlantic. It keeps western Europe significantly warmer than it would otherwise be. The Trade Winds drive the water westward along the equator and at mid-latitudes the water is driven eastwards by the easterlies. These opposing winds cause the currents in the ocean basins to form gyres, or giant loops.