a valley of northern Norway, in Nordland amt (county), draining south-westward from the neighbouring glaciers to the Ranenfjord (lat. 66° 20' N.). There are deposits of iron ore, the working of which was undertaken in 1902 by the Dunderland Iron Ore Company, water-power being provided by the strong Dunderland river. There are also pyrites mines. At the mouth of the river is Mo, a considerable trading village. The valley is remarkable for several stalactite caverns in the limestone, some of the tributary streams flowing for considerable distances underground. From Mo a fine road crosses the mountains to the head-lake of the great Ume river, draining to the Baltic, and from the head of Dunderlandsdal a sequestered bridle-path runs to Saltdal on the Skjerstadfjord, with a branch through the magnificent Junkersdal.