Beneath the United States lies a surprising network of caves shaped over millions of years. Some feel almost otherworldly, ...

Whether it's to build an underground base or discover a way into The End, the possibilities of a good cave seed are endless.

Passive salt caves, like the one I visited ... I’m warm to the idea that simply sitting in a room full of salt when I’m in good health could make me feel even better. I’m not alone, either.