Ocean Gyres Ocean currents flow in predictable patterns. Winds are the predominant driving force of ocean currents, but other driving forces result, such as pressure, temperature, height and salinity gradients, as well as tides. Divergence and convergence zones appear where a current separates, such as where the Pacific gyre collides with the Western United States, or where two currents collide, respectively. Where a gradient exists, potential forms. Gravitational pull from the Earth's moon causes tides, which have greater impact on ocean currents near shore, but nevertheless are a driving force of ocean motion. Sources: Left panel: http://en.wikipedia.org/wiki/Coriolis_effect      Right panel: http://visibleearth.nasa.gov/view_rec.php?id=6204 Another physics phenomenon prominently at play in ocean currents is Ekman transport, which fundamentally is a product of friction or drag between layers of water. The resultant force of wind and water drag  result in current directed at an angle to the surface wind. At a depth of about 100 meters, the drag with higher layers cancels out the driving wind force. Each successively deeper layer is subject to the Coriolis Effect, causing deeper layers to flow in the direction opposite of the surface current. The resultant force of each water layer's motion and the wind direction ends up at a right angle to the wind. source: http://oceanservice.noaa.gov/education/tutorial_currents/media/supp_cur04e.html source: https://www.e-education.psu.edu/earth540/content/c4_p3.html The five major ocean gyres are found in the North Pacific, South Pacific, North Atlantic, South Atlantic, and Indian Ocean.