Lake Nyos | Atlas Obscura. Deadliest lake in the world suffocated over 1,746 people in one night. Crater lakes commonly have high levels of CO2 as they are formed by the volcanic activity happening miles beneath them. Under normal circumstances this gas is released over time as the lake water turns over. But Nyos, rather than releasing the gas, was acting as a high-pressure storage unit. On August 21, 1986, in a Limnic Eruption, the lake erupted. In Cameroon.
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.