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 ...

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 ...

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 ...

Hells Canyon, the deepest river gorge in the United States, likely got rapidly carved 2.1 million years ago when a shifting landscape in Idaho caused a giant lake to start overflowing. That's ...

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 ...

We went deeper than ever before. In this video, we push the outer limits of Pettyjohns Cave, navigating tight crawls, massive chambers, and eerie silence that only gets more intense the farther you go ...

Countryfile saw presenter Matt Baker explore Britain's deepest cave system in Wales, where a slamming door left him visibly ...

Hells Canyon, the deepest river gorge in the United States, was carved just about 2.1 million years ago — making it much younger than the Grand Canyon. (Matthew Morriss) Hells Canyon, the deepest ...