mountain chain extending in a southwest–northeast direction along the Guinea–Côte d'Ivoire–Liberia border. It reaches its highest elevation at Mount Nimba (5,748 feet 【1,752 m】) in Guinea. Surrounded by lowland rain forest to the south and savanna to the north, the mountains are the source of the Nuon (Nipoué, Cestos) and Cavalla rivers, which form the Liberia–Côte d'Ivoire boundary. All three countries have set aside nature and forest reserves on the mountain slopes.

The range has considerable mineral wealth; extensive iron-ore deposits were mined by the Liberian American-Swedish Minerals Company (Lamco) after 1963 and exported via the 168-mile (270-kilometre) company railroad to the port of Buchanan. A mining concession was granted to Consafrique, a European consortium, to mine the Guinean section of the range after an agreement had been reached with Liberia to use the Lamco railway.