Halnefjorden is a large lake on the border of Hordaland and Buskerud counties in Norway. It is located in the municipalities of Hol and Nore og Uvdal in Buskerud county and in Eidfjord municipality in Hordaland county. At 13.61 square kilometres (5.25 sq mi), it is among the largest lakes located on the vast Hardangervidda plateau. The Norwegian National Road 7 runs along the northern shore of the lake, and that is the only road access to the lake.