The world’s longest underwater cave system now stretches an astonishing 524 Kilometers, a hidden labyrinth that, in raw ...

Here’s how to plan a trip to Mammoth Cave National Park.

It dropped down to number two for a while, but more recent exploration confirms Mexico's Ox Bel Ha is officially the longest ...

Why it's incredible: This massive submerged cave system is among the longest in the world and holds a number of spectacular features and remains. Sistema Ox Bel Ha, meaning "three paths of water" in ...

The air is cool and damp. The light shining from behind is low and tinted, while a park ranger's hand hovers over a button. Then, a switch clicks. Light floods a chasm in the stone, a chamber called ...

Step off the desert trail and into Arizona’s longest cave, where crystal formations and subterranean wonders await.

Divers in Mexico's Yucatan Peninsula say they have discovered the world's largest underwater cave. Underwater archaeologists discovered last week that the cave system known as Sac Actun, located near ...