I haven’t been checking up on the latest country in the world (it is called Sealand, isn’t it?) but I was wondering what it takes to have an island of my own without buying one. That place of the coast of the UK is just and anti-aircraft gun platform IIRC, does a new country have to be on an actual rock in the middle of the sea? Can I just dump a load of sand and concrete in the middle of the sea somewhere and proclaim it to be mine and therefore a new country? Could I just grab the latest volcanic land to extrude above the ocean (after its cooled) and procliam it mine if it was outside of soemones territorial waters?
Well, as the (snicker) government of (snicker, chortle) Sealand is finding out, what it really takes to establish your own country is international recognition. 
Although the idea of your very own isleand is cool, have you actually seen Sealand? It looks a little bit like something the Smokers in Waterworld would inhabit.
I used to have a link, but I deleted it. Shouldn’t be hard to find. IIRC, Sealand is actually owned by a corporation now.
Oh, here you go (if you haven’t seen it):
http://www.sealandgov.com/
I believe if you try to email them, you’ll see it goes to a corporation.
Myself, I’d prefer a real island to a floating tin can, but YMMV. 
Sealand’s been around for a while - I remember news items from the late Seventies about its declaration of independence. I think there was something of a fad for this at the time: I vaguely remember some chap declaring himself King of his council flat in some kind of protest about the rates. The UK government is surprisingly tolerant of this sort of eccentricity - providing that the new “nation” thus formed doesn’t actually get any sort of recognition elsewhere, or its occupants aren’t engaged in obvious breaches of UK law.
The most recent piece of real estate to rise out of the ocean still seems to be Surtsey, the volcanic island south of Iceland which appeared in the Sixties. It’s close enough to Iceland that the Icelanders claimed it (as a nature reserve) pretty much automatically, though I haven’t yet found the date when people first set foot on it.
Presumably, in the absence of a prior claim, and if a new island arose outside recognised (or even disputed) territorial waters, the first person to get to it could claim it in their own name… I don’t know what good it would do you, unless you wanted to set up a tax haven or something.
I’ve looked into Sealand before, and it’s quite an interesting story. I’ve even interviewed Sealand’s heir to the throne. Lot’s of other good links on that page.
It’s important to remember that there are at least two kinds of Sealanders, the “real” Sealanders, who are trying to set up a network hub out there, and the “fake” Sealanders, who actually briefly took over the platform and held Michael Bates hostage, and later started issuing false passports.
As someone who deals with issues of sovereignty on a regular basis, I think the “real” Sealanders have a moderately convincing, although very legalistic, argument. Incidentally, the UN has banned the recognition of man-made structures as nations, but Sealand claims to be grandfathered out of that rule. It’s easy to set up your own country; it’s much harder to make anyone else acknowledge your country.
Ich Bin Ein Sealander. Actually, I’m not. Mr. Bates has not invited me to join them, as of yet.