Wind, temperature differences, water density and salinity all play a role in generating ocean currents. Currents may also be influenced by external forces, such as earthquakes, the coriolis effect produced by the Earth's rotation, and the gravitational pull of the Moon.
Ocean currents are cohesive streams that circulate seawater throughout the oceans of the world. These currents may be divided into two categories: surface currents, which are driven largely by wind, and deep water currents, which are influenced more heavily by temperature variations and differences in water salinity. Surface currents only impact a very thin layer of seawater at the surface, while deep water currents, which occur at depths greater than 400 meters, account for the bulk ocean currents.
Ocean currents are complex systems responsible for moving tremendous amounts of seawater as well as storing, transporting and realising thermal energy caused by solar radiation. Currents of seawater are very similar to air currents and other atmospheric patterns in that currents typically adhere to a regular set of specific patterns. These currents may occasionally be disrupted by outside forces, which may temporarily influence or shift currents. Large weather systems, storms and hurricanes may impact surface currents, while underwater earthquakes have the potential to trigger devastating tsunamis.