Lake of Northern Ostrobothnia and Kainuu, Finland
Oulujärvi (Finnish:[ˈou̯luˌjærʋi]) orLake Oulu orUle (Swedish:Ule träsk), is a largelake in theKainuu region of Finland. It is also historically known asLake Cajania from a former name of Kainuu.[3] With an area of 928 square kilometres (358 sq mi) it is thefifth largest lake in the country. The lake is drained by theOulu River, which flows northwestward from the lake into theGulf of Bothnia. Its nickname is the "Kainuu Sea", and it is bordered by the threemunicipalities ofVaala,Paltamo, andKajaani.[2] About 40 percent of the lake is in Vaala.