Abstract: A system for rebuilding beaches which are subject to erosion of sand comprises a sheet of flexible impermeable material placed in the ocean near the shore and anchored to the water bottom with a plurality of landward tethers and a plurality of seaward tethers. A shoreward edge of the sheet parallel to the shoreline is weighted down. A seaward edge of the sheet, also parallel to the shoreline, may be provided with a float device to tend to raise the edge. As waves travel from the ocean toward the beach, the water is deflected under the sheet by the raised seaward edge, and into contact with sand and soil under the sheet, causing the sand and soil to move toward the beach. However, during the backwash of the wave, the weighted beachward edge of the sheet rests on the water bottom, deflecting the water over the sheet and out of contact with the sand and soil under the sheet, preventing movement of sand and soil away from the beach.