The Dry Tortugas are a small group of islands, located in the Gulf of Mexico at the end of the Florida Keys, United States, about 67 miles west of Key West, and 37 miles west of the Marquesas Keys, the closest islands. You can get there by a high speed boat or by seaplane. This was a Civil War prison with its' most notable "guest" Dr. Samuel Mudd who was convicted as being part of the group who assassinated President Lincoln. The tour is fascinating and is worth the day spent. Oh, you can also snorkel here also.