I mentioned before that I'm reading this Ken Jennings map book. It really is mostly pretty dull, but every once in a while there is a neat footnote. Rockall was one of them, but an even better one is
Ferdinandea.
Ferdinandea is a former island near Sicily. A volcano erupted in 1831 and created a new, small, island in the middle of the narrowest part of the Mediterranean Sea. It immediately became a popular tourist destination and caused an international feud between 4 different nations who all tried to claim the new territory. But after only a few months, it crumbled back into the sea, ending all disputes. All disputes until 1986, that is, when the US bombed the underwater island because we thought it was a Libyan submarine. Seriously.
I would have used Ferdinandea as a "where is it?" but it doesn't exist and there are no photos.