Located on the flank of the Poas Volcano in Costa Rica, the Cave of Death just happens to be near some very nice hot springs which have been developed into Recreo Verde. This fine place was our base camp, actually a fabulous cabin, for our work in this area.
And as for the cave, it is a bit of a tourist attraction, and probably one of the few commercial caves where one does not in fact go in the cave. Why? Good question and glad you asked. The reason for the name is fairly simple, as the cave itself is a huge emitter of nearly pure carbon dioxide. This, as one might suspect, is what could mildly be called, "bad air" and it is quite dangerous and often fatal to animals that enter the cave.
But, since carbon dioxide is heavier than air, the "bad air" is mostly along the floor, and in fact pools up at the entrance with the spillover rolling out of the cave and along the ground. How do we know this? Another good question! Guy van Rentergem invented a clever little smoker device out of an e-cigarette machine, which could be placed in specific spots to see exactly where the gases were going. As well, we used a carbon dioxide meter to determine where the gas was and in what concentrations.
And just to be thorough, we tracked the gas with smoke all the way out of the protective barrier at the cave's entrance where it eventually drifts off in the breeze, while staying right along the ground.
***Huge thanks to Recreo Verde for allowing us to study their most interesting little cave. Awesome place to stay on all accounts and really enjoyed it there.