Abstract: The artificial reef of the present invention is constructed from a plurality of structural units each of which is a tetrahedron-shaped sandbag, which are arranged in a talus pile. The reefs are formed by dropping the structural units in the desired locations. The tetrahedron-shape of the structural units provides a self-interlocking structure which can be placed en mass on the sea floor without individual alignment of each bag. The geometry of the reef structure is a sloped bar, a parallel bar, or a V-shaped bar, or combinations thereof. The parallel bars, which run parallel to the shoreline, trap standing waves between the bars to reinforce the incoming waves with a maximum energy focused where the rays of trapped waves cross the wave rays of the incoming swell. A multiple V-shaped bar configuration, with the apex of the V pointing diagonal to the incoming waves creates Bragg reflection patterns which cause crossing wave rays to form local concentrations of wave energy.