A device is provided for preventing shoreline erosion and for rebuilding the sand beach along the shoreline of a large body of water. A series of the devices are placed in side-by-side relation essentially parallel to the shoreline. The device includes a hollow plastic structure fillable with a heavy material, such as cement. The structure has a trapezoidal configuration to lower the center of gravity of the device and includes inclining front and rear walls converging toward each other to the top wall. The hollow plastic structure includes a plurality of tubular members extending from the front wall to the rear wall. The front and rear walls have access apertures opening to the tubular members. The tubular members gradually taper from a predetermined diameter at the access apertures in the front wall to half of the predetermined diameter at the access apertures in the rear wall to reduce the velocity of the flow of water to the large body of water.