US Patent 7404692 Breakwater generating structure

Waves are amplified by a gradual decrease in depth, and when the waves reach a vertical wall 10 of a reef 2, breaking waves are generated by sudden decrease of the water depth. As the breaking waves rush into the upper portion of the reef 2 and pass through the slant slits 14, wave energy is absorbed by the reef 2 and the seat water returns back to the ocean through an opening 11. The sand brought into a reef 2 with the waves are washed away by the return flow 11 so that the sand is not deposited within the reef 2 and the space in the reef 2 is always clear.