The walls of Fort Jefferson are situated on tropical Garden Key, presently part of Dry Tortugas National Park near Key West. There's no fresh water here at all, which makes it hard to imagine how a fort was built.
Dry Tortugas National Park is one of the least visited national parks in the United States, with only visitors per year. This is primarily due to its remote location 70 miles west of Key West. It is also the most aquatic of all the US national park