The Glomma, or Glåma, is Norway's longest and most voluminous river. With a total length of , it has a drainage basin that covers fully 13% of Norway's surface area, all in the southern part of the country. Geography At its fullest length, the river runs from the lake Aursund near Røros in Trøndelag and runs into the Oslofjord at Fredrikstad. Major tributaries include the Vorma River, which drains Lake Mjøsa, joining the Glomma River at Årnes in Nes. The Lågen drains into Lake Mjøsa, collecting …