Exploring Toxic Ice Caves Inside an Active Volcano | Expedition Raw

The cave entrances are all along the side of the rim. We're walking along the summit of Mount Rainier on our way to the East Crater Cave to make a three-dimensional map. So if someone gets lost or hurts, it's easier to conduct a search and rescue operation. Some of the entrances are very steep; you could take a 40-foot free fall followed by several hundred feet of tumbling into toxic air waiting for you at the very bottom.

We're in the crater of an episodically active volcano, so this is not the place that many people go to have fun. Is everybody okay? Good. Rule number one: don't get hurt. My nerves are up the whole time I'm inside the cave. This was fine, but down here's not.

When you hear the beeps go off, it means you're in a very dangerous level of carbon dioxide, and you have to leave right away, or you could go unconscious and die right there. What's alarming is that the risk we're undertaking is worth it to me. The caves are very unique; we're looking at a couple of different things, but they center on possible microbial life that lives in these caves.

A blend of volcanic gases mixing with a high-altitude, dark, icy cave replicates what they expect to find on Europa, the Martian ice caps, or other ice bodies somewhere in the solar system. It's a very exciting alien environment that draws you in, but we've just basically skimmed the surface, which is why we're going to be coming back for many years to come.

Keep my out! All of a sudden, it just started raining down on top of me. One of us, or all of us, just the our fin kicks, or just the pressure waves of our body must have set off this avalanche.