The Jubilee Pool in Penzance is the 'largest, most celebrated Art Deco seawater pool in Britain'. It has always been unheated, but a geothermal section in which the water is heated to 30-35C was recently incorporated into the enormous triangular pool. Now owned by the community and Grade II listed, it was opened in 1935. The C20 Society, who fought to save it from redevelopment in 1990 writes, "Jutting out from the Battery Rocks into Mount’s Bay, the tidal pool was an impressive feat of engineering. It is one of the best surviving pieces of Art Deco architecture in the country." Roger Deakin gives a wonderful account of this 'modernist extravaganza' and his swim there in Waterlog.