Okefenokee Swamp (ōˌkəfənōˈkē) [key], c.600 sq mi (1,550 sq km), c.40 mi (60 km) long and averaging 20 mi (32 km) in width, SE Ga., extending into N Fla. It is a saucer-shaped depression with low ridges and small islands rising above the water and vegetation cover. It abounds in varied wildlife, and is drained by the Suwanee and St. Marys rivers. In Georgia the swamp makes up most of the Okefenokee National Wildlife Refuge (est. 1937).