Akerselva, or Akerselven, is a river which flows through Oslo. It starts at Maridalsvannet in Oslomarka, and follows the urban areas Nordre Aker, Sagene, Grünerløkka, Oslo centre and Grønland, whereby it finally ends at Paulsenkaien and Oset in Bjørvika. The river is considered to be a part of the Nordmarkvassdraget, and has the watercourse number 006.Z. The entire river is about 8.2 kilometres long, and has a difference in altitude of approximately 149 meters.

Earlier, the river gave power to numerous industry companies in Oslo. In the summer of 2008 Kunsthøgskolen i Oslo (The Oslo National Academy of the Arts) will move into this formerly industrial premises. The new campus will be one of the most spacious in Europe.

Akerselven is "Oslo’s green lung”; many parks and nature trails are to be found by its path, from Grønland to Maridalsvannet. A walk from along Akerselven from the rural Frysja down through the different parts of Oslo all the way down to the city centre is an amazing experience and a walk through the history of Oslo.^{[citation needed]} Salmon run and spawn in the upper part of the river.