A honeycomb sea wall (also known as a "seabee") is a coastal defense structure that protects against strong waves and tides. It is constructed as a sloped wall of concrete blocks with hexagonal holes, which makes it look like a honeycomb. These are placed as a revetment over gravel or rock. During strong storms, surging sea water loses energy as it travels down the holes and through gravel at the base of the structure. The water is returned to the sea through underground vents. Water that does not go through the holes is redirected by the concrete wall back into the path of oncoming waves, creating more turbulence. Due to their cost, honeycomb sea walls are often passed over in favor of other forms of "hard" sea defence such as piled rocks or concrete steps.