Waters of Mass DestructionLake Nyos. It gasses people, apparently. From the article (from the mid 80s): "The gas killed all living things within a 15-mile (25km) radius of the lake, and the area is still highly contaminated."
There's now a system to jet the offending gas (CO2) into the air. It has been proposed that this be expanded, which is why all this is a big deal.
Bizarre, though. I never heard of any such disaster.