[Rebelbase]

Yep, a volcanic lake about 600' deep that has a huge amount of decaying plant and animal life at the bottom. I don't recall the process, but somehow the gas builds up pressure until it "pops" like a can of soda, sending a huge plume of CO2 down the valley. Suffocates humans and animals, I think the toll was in excess of 1000+ persons.

[Constitution Day]

Thanks.

I seem to recall the pictures... looked like someone had set off biological weapons.