Lake Nyos

Lake Nyos is a crater lake in the Northwest Region of Cameroon, located about 315 km northwest of Yaoundé, the capital. Nyos is a deep lake high on the flank of an inactive volcano in the Oku volcanic plain along the Cameroon line of volcanic activity. A volcanic dam impounds the lake waters.

A pocket of magma lies beneath the lake and leaks carbon dioxide into the water, changing it into carbonic acid. Nyos is one of only three lakes known to be saturated with carbon dioxide in this way, and therefore prone to limnic eruptions.