The earth might be a big old place, but believe it, or not, apart from a few bits of Antarctica and a few islands between Serbia, and Croatia everywhere has been claimed, well almost everywhere, there’s also Bir Tawil.
Bir Tawil or Bi’r Tawīl has found itself in the anomaly of Terra Nullius due to a map anomaly in the late 19th century.
In 1899 when Egypt and Sudan were British colonies the British drew a map that set the border at the 22nd parallel. The British then being like they are did another map in 1902 that gave a different dividing line. The new map had Egypt losing the Hala’ib Triangle (which is useful), but keeping Bit Tawil.
To cut a long story short both Sudan and Egypt claim the map that suite them best, thus if either were to claim Bir Tawil they would be admitting that they didn’t have the Hala’ib Triangle. And thus we have the situation of no one wanted Bir Tawil.
Due to its unique status and the huge number of weirdos on the internet, many micronations claim Bir Tawil as their own territory. The most famous of which is the Kingdom of North Sudan, who at least went there and planted a flag.