DUNDERLANDSDAL, a valley of northern Norway, draining south-westward from the neighbouring glaciers to the Ranenf ford (lat. 66° 20' N.). Valuable deposits of iron ore (magnetite and pyrites), first worked in 1902, occur here. At the mouth of the river is Mo, a considerable trading village. The valley is remarkable for caverns in the limestone, some of the tributary streams flowing for considerable distances underground.