Which 550 km river is the longest in Finland?

The 550-kilometre Kemijoki is Finland’s longest river.

Also called the Kemi River, the Kemijoki flows through Finnish Lapland, passing near Kemijärvi and Rovaniemi before reaching the Gulf of Bothnia at the coastal city of Kemi. At Rovaniemi, the Ounasjoki joins it, adding water to the river’s substantial drainage system.

The river is important not only geographically but economically. Finland built its first Kemijoki hydroelectric plant at Isohaara between 1945 and 1949, and the river now has 15 power plants. Its hydropower has made the basin one of the country’s most significant electricity-producing regions.

A common mix-up is the Oulujoki, another major Finnish river, or the Tornionjoki, which forms part of the Finland–Sweden border. Neither is as long as the Kemijoki. The name can also be confused with the separate Kem River in Russia.