The bizarre border between Sweden and Finland

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The border between Sweden and Finland contains several enclaves and exclaves, which are pieces of one country’s territory completely surrounded by the other country. This unusual arrangement is a result of historical land swaps and adjustments between Sweden and Russia (which controlled Finland) in the 18th and 19th centuries.

One of the most famous enclaves along this border is Märket Island, located in the Baltic Sea.

Märket is a small island, also known as a skerry, in the Baltic Sea between Sweden and Finland. It is remarkable for being the smallest sea island shared by two countries and for it’s unorthodox border. In 1809, at the end of a Swedish-Russian war the island was divided up in the Treaty of Frederikshamn. At the time the treaty cleanly heaved this unimportant island in two.

Decades later the Russians established a lighthouse on the island. The sea surrounding Märket is dotted with treacherous shoals and navigation in the area is difficult. This lighthouse greatly helped navigation in the Baltic, but it caused a new problem. The lighthouse was erected on the Swedish side of the island and was a low-level border dispute for many years.

Finally in 1981 both countries worked on a solution. They both wanted to share an equal amount of the land area on the island. They also wanted to keep the status quo of the sea border to preserve fishing rights. To meet both these conditions the land border became the bizarre shape that we see today.

A lighthouse, which was built on the island, is jointly maintained by both countries, and its kitchen and living room are in Sweden, while the bedrooms are in Finland.

Below is another map of Märket Island created by Patric Mcgranaghan.