Dry Tortugas National Park
Hop the ferry to the Dry Tortugas National Park; the seven islands, 70 miles west, are the last of the true Keys. Evocative Civil War–era Fort Jefferson is spooky to explore (Samuel Mudd was jailed here for his supposed part in Lincoln’s offing). Snorkel in the coral reefs 10 feet from shore. Don’t miss the bird sanctuaries teeming with sooty terns and frigates on Bush and Long keys.