Maridalen is a valley in the north of Oslo, Norway, just above the suburb of Kjelsås.
Considering that Maridalen is within the Oslo city limits, this area has a very low population density.
Most of the valley is made up of the lake Maridalsvannet, which serves as the primary source of drinking water for 90% of Oslo's population.
A bus route runs along Maridalen, starting at Nydalen Subway Station.
The old church (now in ruins) just north of the lake was dedicated to Margaret the Virgin.