The Okefenokee Swamp is a shallow, 438,000-acre (1,770 km 2), peat-filled wetland straddling the Georgia – Florida border in the United States.A majority of the swamp is protected by the Okefenokee National Wildlife Refuge and the Okefenokee Wilderness.The Okefenokee Swamp is considered to be one of the Seven Natural Wonders of Georgia. The Okefenokee is the largest  blackwater  swamp in North America.he swamp was formed over the past 6,500 years by the accumulation of peat in a shallow basin on the edge of an ancient Atlantic coastal terrace, the geological relic of a Pleistocene estuary.