A few weeks ago, I was up in the Sierra Nevada Mountains by myself for the weekend.

I like doing that sometimes.

The ski mountain I like is about five hours north of L.A.

I usually leave town on a Friday night.

On the way up, I sleep in my van at a rest stop or a campground on public land, and I wake up the next morning and the mountains are right there.

On this trip, I had decided that after a day of skiing, I was going to go explore the Long Valley Caldera.

A caldera is basically a big depression caused by a volcano that has collapsed on itself.

And the Long Valley caldera did that about 700,000 years ago.

It's actually one of the largest calderas in the world.

20 miles by 11 miles.

Right near Mammoth Mountain, where I go skiing.

It looks like just a big, flat, open field covered in sagebrush.

But underground, there's still an active magma chamber that heats the groundwater and forms

some of my favorite things in the world.

Hot Springs.

These little blue pools that pop up all across the field where hot water has bubbled up

and you can just get in and sit there on a really cold day. So on this day, I was searching for

hot springs in the Long Valley Caldera by myself and my van. Oh, and it was after a really big snowstorm.

What could go wrong?

I'm Kelly McEvers, and this is Atlas Obscura,

a celebration of the world's strange, incredible, and wondrous places.

And here at the show, we ask people a lot of questions about the places they go.

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