Basalt Architects has used marine-grade concrete to build Guðlaug Baths, a geothermal pool on Langisandur Beach in Iceland. The baths consist of a three-tiered structure, with a viewing deck on the top, a warm geothermal pool in the middle, and a cooler pool at the bottom. Guðlaug Baths consists of two pools and a viewing deck These three oval-shaped forms are each oriented differently, creating an irregularly shaped volume that nestles in amongst the large boulders of the sea wall. A staircase wraps the exterior, connecting all three levels. "Choosing to put the pool in the rocks maximise...