Definition: The region occupied by any more or less continuous, directed movement of ocean water that flows in one of the Earth's oceans. Ocean Currents are rivers of hot or cold water within the ocean. The currents are generated from the forces acting upon the water like the earth's rotation, the wind, the temperature and salinity differences and the gravitation of the moon. The depth contours, the shoreline and other movements influence the direction and strength of the movements of water that forms a given current.
Comment: Definition modified from http://en.wikipedia.org/wiki/Ocean_current.