Nobody remotely interested in seasteading can be unaware of the world's only artificial oceanic micro nation. With all the trappings of a legitimate country (you can even obtain an official Sealand ID), albeit not recognized as such by the rest of the world, it's a one of a kind oddball in the history of oceanic settlement efforts.
Sealand, originally a British naval base named Roughs Tower, can be found 7.5 miles off the coast of Suffolk, England. Starting in 1967, it was occupied by the family and friends of one Paddy Roy Bates, who infamously claimed it was his own sovereign country. He did not find it empty; in fact it had been the haven of a pirate radio station, which Roy drove out in order to seize the platform for himself. Consider that the first war in Sealand's history, but amusingly, not the only one.
Serious efforts to establish Sealand as a country began in 1975, depending how one defines serious. Roy wrote Sealand's constitution, designed its flag and went to work on the various other accoutrements of a proper state. Though Roy Bates died in 2012 at the age of 91, his surviving family continues to maintain and operate Sealand, though damage from a fire in 2006 has gone largely unrepaired.
The second war in Sealand's history occurred in 1978 when Alexander Achenbach, claiming to be the rightful prime minister of Sealand, hired mercenaries to mount an assault on Sealand while Roy and his wife were absent. The approach was made with helicopters, speedboats and jet skis, briefly taking Roy's son Michael hostage.
Incredibly, like something out of a depressingly low budget action film, Michael singlehandedly got the best of the mercenaries using weapons stockpiled in a secret armory. There were no deaths, and Michael was able to capture Achenbach who he later tried for treason. After Germany sent a diplomat to negotiate for Achenbach's release, Roy and Michael argued this meant Germany had officially recognized Sealand as a real country.
Lest you imagine this was all just for the fun of it, after being safely recovered, Achenbach established the Sealand Rebel Government. He contended he was still the rightful ruler of Sealand, as does Johannes Seiger, his appointed successor. The Sealand Rebel Government remains in existence, and in exile, to this day.
In 2007, the famous Pirate Bay attempted to purchase Sealand for the purpose of offshore data hosting. The sale did not go through, but would have represented the first documented use of an offshore platform, which is also a permanent human settlement, to evade mainland regulations.
What's next for this tiny maybe-a-country? They're soliciting investors and have been for years, as they need to increase revenue to finish repairing the fire damage. There's also all manner of other problems in need of fixing, which tend to accumulate on an artificial structure out to sea. One option could be to layer the main deck with soil and grow trees, as a sustainable source of food.
Another might be to build up. The platform should support more than what's currently built on it, and with so little square footage, it would make good sense to maximize it as a single contiguous enclosed building. The conditions in the North Sea are rarely so pleasant that you especially want to be outside anyways. Expanding vertically would give Sealand the population capacity to take its claims of being a micronation out of the realm of absurdity, and into borderline plausibility.
Rumor has it Wikileaks is in talks to put servers there, as the Pirate Bay once planned to. Could this mean yet more small scale international intrigue? For such a supposedly irrelevant "nation", Sealand sure does seem to get up to interesting shenanigans frequently. But whether the future of Sealand is expansion into an offshore data haven, or to crumble quietly into the sea, it is at the very least a fascinating piece of maritime history.