Pääjärvi may refer to: Lakes. Pääjärvi (Karstula), located in Karstula in the region of Keski-Suomi, Finland. Pääjärvi (Lammi), located between the cities of Hämeenlinna and Hämeenkoski, Finland. Lake Pyaozero (Finnish: Pääjärvi), located in the Republic of Karelia, Russia. Settlements. Pyaozersky, a settlement in the Republic of Karelia, Russia, called Pääjärvi in Finnish. People. Magnus Pääjärvi (born 1991), Swedish ice hockey player
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