Finnish–Swedish border

The Finnish-Swedish border is the border between the countries of Finland and Sweden. Almost the entire border runs through water: along the Tornio River and its tributaries, and in the Gulf of Bothnia. Only a few kilometres of the border are on dry land. Because of the Schengen treaty and the Nordic Passport Union, the border can be crossed mostly freely.

In the north, the Finnish–Swedish border begins from the Treriksröset tripoint at the border of Norway, located in the Koltajärvi lake near Kilpisjärvi, which is also the northernmost point of Sweden. The first 230 metres of the border are in straight lines and marked with border signs. The border continues as a river border first along a small river to Kuohkimajärvi, then along Kuohkimajoki to Kilpisjärvi, then along the rivers Könkämäeno, Muonionjoki and Tornionjoki, a total of 555.5 kilometres down to Tornio. The river border runs along the deepest parts of the rivers (the thalweg), and is not marked with border signs; instead the border location is defined by the official maps of the border protocol. There are some border markers near Tornio where the border runs on land.

In Tornio, the border departs from the river: the centre of Tornio is located west of the river, but belongs to Finland. The border runs in straight lines for 4.03 kilometres between the cities of Tornio and Haparanda, and from there in straight lines 25.31 km as a maritime border mostly through sea, but also through islands including one called Kataja. In 1809 the border went between the islands Kataja and Inakari, but the post-glacial rebound has caused them to join into a single island. The border continues as a maritime border to a point in the Bothnian Bay, where the Finnish and Swedish territorial waters depart from each other.

In the Bothnian Bay and the Bothnian Sea, the Finnish and Swedish territorial waters are separated by international waters. The territorial waters meet again in the Sea of Åland, where the countries have a maritime border of 15 kilometres. The border crosses the island of Märket, which has a 470-metre long, complexly shaped border marked with border signs.

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Wikipedia