The river Elliðaár is situated in the Reykjavík area in the south-west of Iceland. Two small rivers have their source in the volcanic mountain range of Bláfjöll and stream down to the lake Elliðavatn in the eastern suburban border of the city, its outlet forming the river. On their way, they pass through the nature reserve area of Heiðmörk.
On its way to the sea, which is reached in the bay Elliðavogur in Reykjavík, not far from the open-air folk museum of Árbæjarsafn in Árbær, the river cascades over several small waterfalls within the boundary of the city.
Salmon fishing in the river is excellent although very expensive.
The valley Elliðaárdalur is one of the green recreational areas of Reykjavík with hiking and bicycle paths. There are also a swimming pool, a small ski lift and horse riding facilities in the valley.
Very interesting and varied bird life is to be found in the valley including swans and 8 different species of ducks. All together, 60 species of birds can be found here. There are also many song birds such as the thrush.
In 1921, the second hydroelectric power station in the country was constructed here and is still in use, the first being situated in the nearby town of Hafnarfjörður. A museum in the building tells the story of the electrification in Reykjavík.