Richard Strauss's concerto "Thus Spoke Zarathustra" blared over a portable radio on the Liberty, a two-story houseboat off the self-proclaimed crypto micronation of "Liberland," a muddy Danube island on the border of Serbia and Croatia.

The music — an ode to Friedrich Nietzsche's novel about the doctrine of the "superman" — played on would-be state radio to celebrate what Liberlanders see as a de facto border deal for their country, which was founded with a mix of right-wing libertarianism and technology like crypto on the marshy island of Gornja Siga.

Nineteenth century straightening of the Danube left some small peninsulas of the once meandering river that had been part of Croatia stranded on the Serbian side of the river’s current course, with the 7-kilometer-long island of Gornja Siga, once part of Serbia, marooned closer to the Croatian bank.