Neighbors

https://commons.wikimedia.org/wiki/File:Velez_de_la_Gomera.jpg

Until 1934, Peñón de Vélez de la Gomera was a Spanish island off the coast of North Africa.

But then a thunderstorm washed enough sand into the channel to create an isthmus to the Moroccan shore.

So now the island is a Spanish exclave on a peninsula, and the two nations share the world’s shortest border.