Seen from the ferry the low brick structure surrounding the fort is barely visible. But seen close up it is clearly an engineering feat on it's own terms:Seen at sunset, above and the moat seen from the bridge at the entrance to the fort, below: In the picture above the moat is at it's widest, separating the walls of the fort from what the Park Service is pleased to call the "Day Use Area" and, closer to the trees, the "Overflow Camp Sites" if the main camp sites are all full. The moat was originally designed to keep attacking boats away from the walls themselves because those tricky enemies might load them up with explosives and drive them into the fort walls to blow them up. The moat would prevent that sort of dastardly attack. As seen from the top of the fort the moat wall has, on certain sides of the building, collected dunes of sand that have washed up against the outer wall. Thus the moat also keeps the motion of the ocean itself away from the fragile base of the brick fort.The same spot seen from below shows how substantial the land accumulation has become on this, the eastern side of Fort Jefferson. Further to the north the moat itself has become filled with sand creating a rather pleasant, protected beach, not that swimming is allowed here or in the moat itself, but I don't see how one could be prevented from enjoying the sandy expanse... Of course walking the moat is one of the pleasures of visiting Fort Jefferson, which at 70 miles (110kms) east of key west is the most isolated National park in the United States. All visitors should walk the moat, and those lucky enough to be camping or visiting on their own boats can take the time to circumnavigate the fort after the crowds who came by ferry have departed. They leave at 2:45pm so there is plenty of time to enjoy the moat. I met some of the local fauna on my excursion too:
The moat wall has a break in it, at the northwest corner which allows sea water to roll in and out to keep the water close to the fort good and fresh. For the convenience of park patrons they have built a little footbridge to span the gap. I took the time to swim out along the moat wall on the outside but I have to say I didn't find it that interesting, certainly not as interesting as the coral heads further to the west. I guess it depends on your expectations.
The moat makes for a picturesque addition to the scene out at the fort quite aside form it's usefulness: But I think, in the final analysis, moats themselves are objects of a certain fascination in a country too new to ever have been involved in medieval European siege warfare, so the moat at Fort Jefferson, still fully functional has the merit of being unique in most visitor's experience:Taken like that it could be a crusader castle in the Levant. Not a National Park in Florida.