large forest morass lying mainly in Collier county, southern Florida, U.S., and covering 2,400 square miles (6,200 square km). The region merges into the swampy Everglades to the east and south. It is dominated by cypress trees, and wildlife is abundant. Sunniland, a village in the swamp about 40 miles (65 km) southeast of Fort Myers, was the site of the first oil wells in Florida. The Seminole and Miccosukee Indians have reservations in the area, which is crossed west to east by the Everglades Parkway.

Big Cypress National Preserve, established in 1974, covers some 1,200 square miles (3,100 square km) on the swamp's eastern half. It was created because of the importance of its watershed to Everglades National Park, which borders it on the south. The preserve provides habitat for such endangered species as the Florida cougar (Felis concolor coryi).