Key West is the end-of-the-line in the Florida Keys. Reach it and the rewards are many. The nightlife is plentiful and the local population is wonderfully welcoming. Underwater, get ready for big. The colossal 522-foot General Hoyt S. Vandenberg is one of the biggest artificial reefs in the world. This retired Air Force missile-tracking ship was sunk in 2009 on the sand bottom at 150 feet.