Finland–Sweden border border continues south into the northern Baltic Sea to a point where it meets the zone border of Estonia. The tripoint between the economic zones is defined by a treaty signed in 2001. The Finnish–Swedish border was created in 1809 by the Treaty of Fredrikshamn, as Sweden ceded Finland over to Russia. The course of the border was described in the fifth article of the treaty, without great detail. The borders were agreed to be the Sea of Åland, the Gulf of Bothnia, and the rivers Tornionjoki and Muonionjoki. Islands in the sea belonged to whichever country was the nearest
Finland–Russia border Finnish reindeer fence. Unlike other Western countries, the government of Finland did not protect illegal border crossers but returned them to the Soviet authorities if captured. Illegal border crossers had to get through Finland to e.g. Sweden in order to defect to the West. In the Moscow Armistice signed on 1944 between Finland, Soviet Union and United Kingdom, a small peninsula towards the Gulf of Finland, Porkkala, was rented to Soviet Union as a military base. This created in effect a southern border crossing to the Soviet exclave, operating all the way to 1956. Border crossings were in and .