breakwater

noun

1. 1.A construction in or around a harbour designed to break the force of the sea and to provide shelter for vessels lying inside
2. 2.A low bulkhead across the forecastle deck of a ship which diverts water breaking over the bows into the scuppers
3. 3.On beaches: a wooden or concrete barrier, usually perpendicular to the shore, intended to prevent the movement of sand along a coast.