Los Angeles may be right next to the Pacific Ocean, but theres also a hidden sea of swimming pools that dot its urban sprawl. Those 43,123 pools have been painstakingly chronicled in a new research volume dubbed the Big Atlas of LA Pools, which was put together by cartographer Joseph K. Lee and designer Benedikt Gross. The pair ran aerial photos through computer imaging and human eyeballs on Amazons Mechanical Turk to determine just how many pools there are in LA, while highlighting popular shapes and locations.