Paatsjoki

Infobox_River
river_name = Paatsjoki River

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image_size =
caption = Harefossen and the Paatsjoki River
origin = Lake Inari
mouth = Varangerfjord
basin_countries = flagicon|Finland Finland
flagicon|Norway Norway
flagicon|Russia Russia
length = 145 km
elevation =
mouth_elevation =
discharge =
watershed = 18,404 km²

The Paatsjoki River ( _fi. Paatsjoki, _sm. Paajokk, _sm. Báhaveaijohka, _no. Pasvikelva, _sv. Pasvik älv, _ru. Паз or Патсойоки) is the outlet from Lake Inari in Finland and flows through Norway and Russia to discharge into the Varangerfjord, not far from Kirkenes. The Varangerfjord connects with the Barents Sea. It has a watershed of 18,404 km², and is 145 km long.

A series of hydroelectric stations, known as the Paatsjoki River Hydroelectric Plants, are located on the river.

Since the end of the Continuation War in 1944, the river has marked parts of the border between Norway and Russia.

The river provides good fishing opportunities for Atlantic salmon, although fishermen must ensure that their fishing lines do not cross the border.