Ocean motion is the collective term for the various movements of the ocean, including tides, swells, eddies, WAVES, currents, and ebbs. Tides are the regular rise and fall of the sea level caused by the gravitational pull of the moon and sun. Swells are long, rolling WAVES that form in the open ocean due to wind and storms. Eddies are circular currents that form when water moves around an obstacle or in a different direction than the main CURRENT. WAVES are the up-and-down motion of the ocean surface caused by wind. Currents are the continuous, horizontal movement of water in the ocean. Ebbs are the receding of the TIDE. All of these motions combine to create the dynamic environment of the ocean.