Hallingdalselva (Hallingdal river) is a river which flows through the valley and traditional district of Hallingdal in Buskerud County, Norway.
The Gulaþing received delegates from Lyngør in the south to north of Ålesund, and its laws were observed from the eastern inland valleys of Valdres and Hallingdal to the Faroe Islands in the west.
A number of rivers flow into the Hallingdal River including the Votna, Lya, Hemsil, Todøla and Rukkedøla.
Olav Thon (born 29 June 1923 in Ål, Hallingdal) is a Norwegian real estate developer and listed in the Forbes list of billionaires as the 198th richest person in the world with a net worth of $6 billion as of March 2013.