Beneath the Earth’s surface lies a world so extreme and isolated that it seems more like an alien planet than part of our own. Veryovkina Cave, the deepest known cave on Earth, plunges a staggering ...

Why it's incredible: The cave is so deep, the world's tallest building could fit inside it. The Hranice Abyss — or "Hranická propast," in Czech — is the deepest known freshwater cave in the world.

I'm a severe claustrophobe. After getting trapped in a slide in my local McDonald's at five years old, I swore off all tight and dark spaces forever. So it's not entirely surprising that I couldn't ...

The Hranicka Abyss is at least 1,325 feet deep, and likely goes down further. — -- A team of explorers believe they have discovered the deepest known underwater cavern the world in eastern Czech ...

June 15, 2006 — -- "Nightline" joined forces with writer Tim Zimmerman and filmmaker Gordon Hiles, who documented an ambitious dive to one of the world's deepest, most dangerous underwater caves.

CEDAR FALLS — A team of NASA-funded University of Northern Iowa researchers is exploring some of the deepest caves in the United States to uncover secrets about life in extreme environments — and ...

On this episode, we hear how a team of researchers at the University of Northern Iowa is exploring the deepest caves in the U.S. with NASA funding. This could inform the search for life on other ...

This summer, Richard Brown and five others from around the country hiked almost 30 miles into the Bob Marshall Wilderness to explore an underground wilderness few have seen. More people have walked on ...