In the center of southern Florida is a lake called Lake Okeechobee. It is the seventh largest freshwater lake in the United States and the second largest freshwater lake entirely within the lower 48 states. Okeechobee is 730 square miles (1,890 km²), about half the size of the state of Rhode Island, and is very shallow for a lake of its size, with an average depth of only 9 feet (3 m).