The fort, which takes up an entire island, was started in the 1840's, to protect the Gulf of Mexico, but was never completed. Seems the Army Corps of Engineers made a little calculation error: the fort was too heavy for the island! In any case, it was used as a prisoner of war camp during the Civil War, it's where Dr. Mudd ended up. The parade ground in the middle attracts all sorts of migrating birds; we saw falcons and owls and nightjars and plenty of warblers. We also camped out on the island for the two nights we were there, which was much better than spending the night on the boat. We traveled to some nearby islands for birding and snorkeling and picnicking, and enjoyed the hot and sunny and clear weather. The trip back to Key West was in the daytime, to look for various pelagic birds, such as Bridled Terns and Audubon's Shearwaters. Luckily for Wes, the organizer, we didn't see any Black Noddies or White-tailed Tropicbirds, and had a great time, so we'll probably do it again someday.