The shortest international border in the world is between which two countries?

For most of its history, Peñón de Vélez de la Gomera was an unassuming rocky isle off the Moroccan coast. During the early 16th century, the island was used as a refuge and a base of operations by groups of local pirates who regularly attacked Spanish vessels across the Mediterranean Sea. To put an end to the constant corsair raids, a Spanish naval brigade led by Pedro Navarro captured the island in 1508.

In the decades that followed, the island changed hands a couple of times until the Spaniards finally retook it in 1564, controlling this miniscule crag ever since. In 1930, a 7.0-magnitude earthquake trembled the area, moving the Iberian and the African Plates against each other. The massive quake was so strong that the ensuing deposition of sand formed a narrow 85-meter-long isthmus that linked Peñón with the Moroccan mainland, making it a de-facto peninsula.

The then newly formed tombolo has created some unintended consequences, as now Morocco and Spain shared a new 80-meter-wide border, recognized as the world’s shortest international border. While the skerry has lost all of its once strategic importance, it is still claimed by both Morocco and Spain, while the latter keeps a military base at its confines, inhabited solely by soldiers.