Turquoise waters lap against the red brick walls of Fort Jefferson at Dry Tortugas National Park in Florida. Almost 70 miles west of Key West, the 100-square mile park is mostly open water with seven small islands. On Garden Key, Fort Jefferson tells an important story about America’s shipping and military history. Accessible only by boat or seaplane, Dry Tortugas also offers amazing underwater attractions including superlative coral reefs and marine life. Photo by Jose Torres (www.sharetheexperience.org).