Volcanic lake gasesIn 1986, more than 1700 people died when toxic gas erupted from Lake Nyos, a volcanic lake in the West African nation of Cameroon. The gas was carbon dioxide which, being more dense than air, hugged the ground and flowed down valleys. The cloud travelled as far as 15 miles (25 km) from the lake. It was moving fast enough to flatten vegetation, including a few trees. In addition to the human deaths caused by suffocation, 845 people were hospitalized and 3,000 cattle died. Lake Nyos is a few square kilometres in area, and is around 200 m deep. It is situated in the crater formed from the collapse of the pipe feeding a now extinct volcano.