Located in Southeastern Georgia, about 4 to 5 hours drive from Atlanta, the Okefenokee Swamp is the largest Swamp in North America, approximately 700 square miles (1800 km²).
We visited it last saturday. It had rained a lot during the preceding days and according to the guide, the water level was about 3 feet (1m) higher that normal. Water depth in the swamp is usually shallow, seldom greater than nine feet. Unlike what it seems (the water looks black), the Okefenokee water is clean and drinkable, but it is stained by tannins produced by decaying vegetation. It also makes the swamp water be very acidic, with a pH of 3.7.

Obviously a swamp is not a forest and hiking is not the best way to visit it, so we took the one-hour boat tour. There is an extensive network of canoe trails in the swamp, over 120 miles (200km) of trails, the ones we saw were very scenic. Most trails are actual natural canals and were used for ages by the Seminole, the Indian tribe that used to live in the area.
Even if you don't want to take a boat tour or rent a canoe, there is a pretty nice broadwalk built on the water that will lead you pretty far in the swamp.

The swamp vegetation by itself makes the trip worthwile. Lots of Pond Cypres covered with spanish moss (again), water lillies, pines, palmettos, all growing directly in the water or on dry land, in the numerous islands there are in the swamps. When I say dry, everything is relative, they would probably be called marsh somewhere else but in comparaison with the swamp they look dry...

The swamp is also rich in birds, fishes, amphibians and reptiles including the American alligator! 20,000 of them live in the swamp if I remember correctly what the guide said, and we saw quite a few of them, some small, some big (more than 10ft - 3m in length), some far away and some just close enough to make you feel a little nervous and to make you take seriously the guide instructions about letting your hands inside the boat;-)

Pictures posted here (public): www.windal.net/gallery/Okefenokee and here (private access).