For centuries, humans have lived underground. Today, that ancient practice is under dire threat—even as cave life makes more ...

Billionaires are building ultra-luxury doomsday bunkers that rival five-star resorts with lavish amenities beneath the earth.

If you're looking for a family vacation that involves crawling through caves, hiking underground suspension bridges, or zip ...

That gust of cool air is what led two National Park Service employees to stumble upon Crystal Cave while fishing at a nearby ...

After hours of crawling, climbing, and navigating pitch-black passages, we finally reached it - a roaring waterfall buried 3 ...