Lake Nyos. Today, the lake also poses a threat because its natural wall is weakening. A geological tremor could cause this natural levée to give way, allowing water to rush into downstream villages all the way into Nigeria and allowing much carbon dioxide to escape.
Lake Nyos is a 2km long crater lake located in the North Western part of Cameroon. The lake has a magma chamber beneath it, which constantly seeps Carbon dioxide into the lake, changing the water into carbonic acid. Over thousands of years of carbon dioxide seeping into the lake, it has become saturated with carbon dioxide.
Asphyxiation by Limnic eruption may sound like fiction; however, that's exactly what happened to 1700 people near Lake Nyos in 1986. Learn how to survive.