Lake Okeechobee
The vast, shallow "Lake O" at the heart of Florida
Lake Okeechobee is the liquid heart of South Florida — a huge, almost perfectly round sheet of fresh water covering about 730 square miles (1,900 km²), the largest lake in Florida and one of the largest freshwater lakes lying entirely within the lower 48 states. Its name comes from the Hitchiti words for "big water," and big it is in area, even as it is astonishingly shallow, averaging only about nine feet deep.
Historically the lake brimmed over its southern rim during the wet season and spread south in a slow sheet that fed the Everglades. After deadly hurricane floods in the 1920s, the earthen Herbert Hoover Dike was raised around it, cutting that natural overflow and turning the lake into a managed reservoir for the farms and cities around it. Balancing its water level — and the polluted discharges sent east and west to the coasts — is now one of Florida's hardest environmental problems.