These are driven by the Trade Winds. In between is a weak eastward-moving Equatorial Countercurrent. Equatorial currents move at about 2-4 miles per day which allows for maximum heating. When the warm currents near the continents they are deflected north and south by the continents and the Coriolis effect. At about 40 N and S the Prevailing Westerly winds deflect the currents to the east.
Water cools as it moves eastward.
Reaching the continents the current is again deflected by the continent and Coriolis effect, completing the gyre. Geostrophic Currents Wind movement and the Coriolis effect combine to cause currents to move at 45 to the actual wind direction. The surface layer drags the next layer of seawater below it which is deflected even farther than the surface layer. This continues downward with depth all the way to the ocean bottom. However, at an average wind speed of 30 mph at a depth of 300 feet the water is moving slowly in the opposite direction from that at the surface.