[3] The stratovolcano rises to 3,011 metres (9,879 ft) above sea level, and is cut by a large caldera.

One of these craters holds Lake Oku, from which flows of basalt issued in the north, and of rhyolitic and phonolitic lavas in the south.

This site includes several plant species endemic to the Kilum-Ijim area, and is of extremely high conservation importance.

Based on satellite images, between 1958 and 1988 about half of the forest was lost, although regeneration began soon after the conservation project was started in 1987.

[7] The montane grassland above the forest belt is home to the endemic Mittendorf's striped grass mouse.