The only unwanted piece on earth is Bir Tawil, between Sudan and Egypt. British colonial border changes resulted in two pieces of barren land being switched, one with access to the sea, and one without. Both countries argue they should have the seaside, effectively leaving Bir Tawil up for grabs.
Map of the disputed border between Egypt and Sudan. Both countries claim sovereignty over the Hala'ib Triangle, but neither country wants Bir Tawil, which is then the only unclaimed territory outside of Antarctica.
The long read: In an American dad claimed a tiny parcel of African land to make his daughter a princess. But Jack Shenker had got there first – and learned that states and borders are volatile and delicate things