Sealand

http://commons.wikimedia.org/wiki/File:Sealand_fortress.jpg

Behold the Principality of Sealand, a self-declared “micronation” on an old sea fort in the North Sea.

Its population is only five, but it has its own government (“Their Royal Highnesses Prince Roy and Princess Joan of Sealand”), constitution, government bureaus, senate, postage stamps, and currency.

And, now, it has an official athlete: In 2003 Darren Blackburn of Oakville, Ontario, Canada, started representing Sealand in local marathons and off-trail races. Presumably short ones.