Ocean waves are undulations of the ocean surface, generally
the result of the action of wind on the water surface. At sea, there is
no overall translational movement of the water particles: they move up and
forward with the crest, down and backward with the trough with the trough,
describing a vertical circle. Near the shore, friction with the bottom causes
increased wave height, and the wave breaks against the land. Waves thus
cause much coastal erosion.