Abstract: A mound breakwater comprises an internal core, one or more filter layers of relatively fine material over the core and an armor layer of relatively coarser material over the filter layers. The armor layer protects the structure from breaking waves. The armor layer in the vertical zone between the mean sea levels is thickened with reference to the thickness of the rest of the height of the armor layer. This thickening is achieved by having a uniform slope on the external seaward facing profile of the armor layer but having a concave or deeper or angled internal profile of the armor between the mean sea levels. The internal profile may be angular, truncated, curved, or the like.