Cumberland Island is one of the Sea Islands. It is located on the Atlantic Ocean off the coast of the U.S. state of Georgia and is part of Camden County (). The island is 17.5 miles (28 km) long, with an area of 36,415 acres (14,735 ha), including 16,850 acres (6820 ha) of marsh, mud flats, and tidal creeks. There is no bridge to the island; the most convenient boat access is from the town of St. Marys, Georgia.
Most of Cumberland Island is part of Cumberland Island National Seashore, but there are also many private properties. Much of the public land is managed as wilderness area.
Large tracts of the island had been purchased for winter retreats during America's Gilded Age. The estates include:
