Isolated 70 miles west of Key West, the islands of Dry Tortugas National Park appear to arise as if by magic, floating atop the waters of the Gulf of Mexico. Discovered by Juan Ponce de Le n over 500 years ago, Tortugas is North America's second-oldest persistent place name. The adjacent Florida Strait provided essential passageway for navies, ships of commerce, pirates, and privateers. Its reefs claimed hundreds of ships over the centuries. The nation's...