Borders

Did you know that a small lighthouse once forced Sweden and Finland to change their border?

Märket is a tiny, rocky island located in the northern Baltic Sea, shared by Sweden and Finland. The island, which measures only about 300 meters long, has a fascinating history—especially when it comes to borders. In 1885, Finland built a lighthouse on the island to help guide ships through the treacherous waters of the archipelago. However, there was one significant problem: the lighthouse was accidentally constructed on the Swedish side of the island.

This unintentional mistake set off a series of diplomatic negotiations. In 1985, nearly 100 years later, Sweden and Finland agreed to resolve the situation by redrawing their border, but instead of a straight line across the island, the new boundary zigzagged around the lighthouse, ensuring that the structure remained under Finnish control while preventing Sweden from losing any land.

What makes this case particularly intriguing is that Märket is one of the few places in the world where a border was altered specifically due to the location of a building. The unique decision to modify the border just for the lighthouse is a rare example of countries compromising over an insignificant geographical feature to maintain diplomatic relations.

Märket’s lighthouse continues to be a symbol of cooperation between Sweden and Finland, a reminder of how even the smallest of structures can lead to significant changes in international boundaries. The island now serves as a shared symbol of the two nations’ long history of peaceful coexistence.

So, do you think the countries made the right decision to change the border just for a lighthouse? Would you have handled it the same way? Let us know your thoughts in the comments below!