Abstract: A structure for dissipating the energy of waves impinging on a shore is disclosed which includes one or more rows of modules positioned adjacent the shore. Each module incorporates a number of vanes. The vanes are shaped and spaced so that a number of venturi passages are defined between the vanes. Each vane has a frontal portion which faces away from the shore, and is inclined from the vertical so that it slopes away from the shore to define an entrapment chamber which forces an oncoming wave to pass through the venturi passages rather than over the module or be reflected. The sides of the passages converge from front to back. A longitudinally extending hub causes the passages to converge also in the vertical direction. Each vane may be X-shaped and substantially symmetrical about a vertical plane through its center. The modules are cast from a cementitious material and may incorporate a number of vanes joined together at the hub which is located at the center of the X.