Someone with a very large back hoe or a plentiful supply of dynamite came to the north shore of Boca Chica Key, at Mile Marker Eight and blew the bejeezus out of the limestone rock. They call these cuts in the rock the Submarine Pens. Thus one could reasonably assume that they were created to dock submarines in... However when you visit these very expensive holes in the water it becomes obvious the most you could do with them is...swim in them!
I don't know who dug them and I don't know when they were created but there are fully seven rectangular holes in the limestone, and to me as a veteran of the Canal they look wider and are definitely longer than the thousand-foot locks of Panama's Eighth Wonder of the World. They also appear to be a great deal less useful, even though they do look quite pretty in a pastoral, unmilitary sort of way: 
These holes in the water could be Key West's Stonehenge or perhaps, viewed from the air, they could be the island's crop circles or cousins to the enormous figures drawn in the deserts of South America. Submarines? I don't think so. I've poked around online and the only mention I can find of submarines and Key West are the official docks at Truman Annex, where the Navy was based for a long time. On the north side of Boca Chica Key the long arm of military militariness is still felt at the inner end of the road past the last pens:
The gate has a shiny new lock to protect the radar installation for the nearby Naval Air Station airfield where Navy jets take practice flights:
Other than the radar dome there is no visible purpose for the road anymore. The Navy owns the land and the mangroves on the other side but the street itself is deteriorating visibly and the bushes are growing out of control:
The thing about the "submarine pens" is that there are no structures alongside them, there are no docks, no cement no signs of any of the shoreside support systems that ships need when they come into port. So the conclusion one draws is that someone somewhere decided to hew out of the living rock a proposal to dock submarines 8 miles east of Key West Harbor across waters too thin to float a sub and instead of completing the channel first, they decided to carve out the pens? If true these things are the most expensive toilet seats the Navy ever sat on. But they do make a pleasant recreational area for Keys civilians, I must say. 
And clearly some locals have taken advantage of these unused giant swimming pools. I found a camp site complete with fire ring, tables and chairs and pool "facilities."
This place has been floating around in my consciousness forever, because I have heard people talk about the pens, but I have never previously bothered to come out here. Why? I don't know really despite my self anointed tag as an explorer. Now that I have come out here I feel like a kid discovering a huge new playground, and I'm guessing that weekdays in summer I shall find a corner or two within this "park" I can enjoy by myself on a hot sticky afternoon.
And clearly some locals have taken advantage of these unused giant swimming pools. I found a camp site complete with fire ring, tables and chairs and pool "facilities."This place has been floating around in my consciousness forever, because I have heard people talk about the pens, but I have never previously bothered to come out here. Why? I don't know really despite my self anointed tag as an explorer. Now that I have come out here I feel like a kid discovering a huge new playground, and I'm guessing that weekdays in summer I shall find a corner or two within this "park" I can enjoy by myself on a hot sticky afternoon. 
I mentioned to my colleague Diggy that I was planning a trip to explore the submarine pens and he looked at me quizzically, declining to ride his Honda 750 "all the way out" to Mile Marker 8 only to get stopped by a Navy Guard. "Those places are on the Navy base aren't they?" said this Conch graduate of Key West High School. That misconception stayed with me as I swung off Highway One at the Navy Base entrance.
The Navy owns most of the land on Boca Chica ("small mouth" in Spanish) Key, with an active Naval Air Station south of Highway One which bisects the island. On the north side of the island, accessed from the ramped Boca Chica exit from Highway one, lies the mystery of the submarine pens. 
The access road runs parallel to Highway One and then passes through some broken gates. As I rode the Bonneville through the gates I wondered, in a rather paranoiac state of mind, if armed Navy guards were going to leap out of the casuarina trees, armed to the teeth with camouflage sprouting from their helmets. No such thing came to pass, as I rumbled down the tatty old access road. In the distance, beyond Highway One, I could see the hangars at Boca Chica glowing in the evening sun:
And alongside the access road the old outlines of cement bunkers, probably ammunition magazines rose out of the mangroves like large immobile turtles: 
I first rode to the end of the road, snapping pictures as I went, still half wondering if I was in fact trespassing, but after I got to the locked gate I realised that I was alone on an empty, unmarked street open to all. The fact that we in the Keys live on small slivers of land necessarily gives these extra strips of open space value out of all proportion to what you see here. This is an excellent piece of parkland right off my commute and I can see strapping a folding chair to my saddlebag, stuffing a thermos of tea inside the same saddlebag and taking an afternoon to sit in the shade and read in peace and quiet, far from the distractions of modern life. No bums, no radios no nothing to disturb me or my motorcycle.
It isn't as though I have explored the whole place yet, so next time I will have to poke a little bit further, ride a little bit deeper into the undergrowth and check out a few more views.
Nevertheless I don't think that, picturesque though they may be, the Submarine Pens of Boca Chica Key are ever going to reveal the whys and wherefores of their existence.
The access road runs parallel to Highway One and then passes through some broken gates. As I rode the Bonneville through the gates I wondered, in a rather paranoiac state of mind, if armed Navy guards were going to leap out of the casuarina trees, armed to the teeth with camouflage sprouting from their helmets. No such thing came to pass, as I rumbled down the tatty old access road. In the distance, beyond Highway One, I could see the hangars at Boca Chica glowing in the evening sun:And alongside the access road the old outlines of cement bunkers, probably ammunition magazines rose out of the mangroves like large immobile turtles: I first rode to the end of the road, snapping pictures as I went, still half wondering if I was in fact trespassing, but after I got to the locked gate I realised that I was alone on an empty, unmarked street open to all. The fact that we in the Keys live on small slivers of land necessarily gives these extra strips of open space value out of all proportion to what you see here. This is an excellent piece of parkland right off my commute and I can see strapping a folding chair to my saddlebag, stuffing a thermos of tea inside the same saddlebag and taking an afternoon to sit in the shade and read in peace and quiet, far from the distractions of modern life. No bums, no radios no nothing to disturb me or my motorcycle. It isn't as though I have explored the whole place yet, so next time I will have to poke a little bit further, ride a little bit deeper into the undergrowth and check out a few more views. Nevertheless I don't think that, picturesque though they may be, the Submarine Pens of Boca Chica Key are ever going to reveal the whys and wherefores of their existence. 