valley, along the lower course of the Rana River, north-central Norway. On the Arctic Circle, it extends about 30 miles (50 km) northeast from Rana Fjord, an inlet of the North Sea. Rich deposits of magnetite and hematite in the valley were mined to supply the ironworks and steelworks at Mo on the mouth of the river. Dunderlands valley is also known for its scenic limestone caverns and underground streams.