Mount Oku, Volcanic mountain in Bui, Cameroon.

Mount Oku is a volcanic peak in the Bui division of northwestern Cameroon and one of the country's highest points. The summit opens onto a wide plateau of grassland and bog, marked by dark volcanic rock that emerges from the ground across the top.

Mount Oku is a stratovolcano of the Cameroon Volcanic Line built from basaltic and hawaiitic lavas, later trachytes, and thick trachytic and rhyolitic ignimbrites up to 1,000 m deep. Some rocks date to 24.9–22.1 million years ago, but much more recent eruptions produced pyroclastic cones and explosion craters. One crater now holds Lake Oku, source of basalt flows to the north and rhyolitic and phonolitic lavas to the south.

The Oku people, who give the mountain its name, have farmed and settled these slopes for generations, and their villages are still visible on the way up. This close tie between the community and the land is something a visitor can sense just by passing through the area.

Warm layers and sturdy footwear are important, as the plateau stays cool and wet even when it is dry lower down. Hiring a local guide makes it easier to navigate the slopes and find the clearest paths to the top.

A sphagnum bog was discovered near the summit at 2,900 m in 1997, the highest of its kind in West Africa. It holds plant species endemic to the Kilum-Ijim area, and the surrounding forest is home to animals found nowhere else, including the Lake Oku clawed frog and the Mount Oku caecilian.