For only $20 more per person, one can camp, overnight, on Garden Key next to Fort Jefferson! This requires reserving a spot many (many) months in advance, as you can see how many camspites there are on this island. As I was traveling with my niece Zinnia, who in addition to being an Intrepid Starforter is also an Experienced and Enthusiastic Camper-Person, I had briefly contemplated the possibility of spending the night next to a starfort. Part of my expectation would have been at least the possibility of sneaking into the fort at night, and were this almost any other American starfort, that might be possible...but Park Rangers live in the fort, and a full moat pretty much reduces the number of potential entrances into the fort to one, the bridge over the moat, so how neaky would that be. Plus, I hate camping! In the end the decision came down to that. In the distance you can see the informational sign Touring the Underworld.