Sistema Sac Actun, the world's largest underwater cave system, spans an impressive 215 miles. This subterranean network of tunnels and crystal-clear waterways is a geological masterpiece with ...

A Twinkling Wonder Tucked away in New Zealand, the Waitomo Glowworm Caves offer a celestial experience. Visitors glide ...

Take an otherworldly journey through Hang Son Doong, the world's largest cave located in Vietnam. The cave is more than 500 feet tall, 650 feet wide, and 29,500 feet long. Video courtesy of Ryan ...

two of the top three largest known caves in the world. To get there, a punishing path and 90 percent humidity test even the fittest hiker. A walk for the fortunate few: Only a limited number of ...

Venturing into the heart of the earth to discover the Cave of Crystals is an adventure like no other. Located in Naica, Mexico, this subterranean marvel houses the world's largest natural crystals ...

For just a few weeks a year, sunbeams shine two hundred metres down through a hole in the cave roof, illumining the underground world. Filming this natural lightshow successfully relied on it ...

The British team found that Deer Cave stretched for nearly two miles, and for a decade afterward it stood as the world’s largest known cave passage. In 1991 a cave discovered in Vietnam ...

It's roughly 200 miles south of Bangkok, and one of the most photographed caves in the world. The world's largest cave is the Son Doong Cave in Vietnam. Located in the Quang Binh province ...

the sound can be heard anywhere from within the cave system, which covers about 64 acres (260,000 square meters). That makes it the largest musical instrument in the world. We’ll save the ...

Sistema Sac Actun is the world’s largest underwater cave system. Stretching an astonishing 215 miles, this submerged labyrinth of tunnels, caverns, and crystal-clear waterways is not only a ...

Discovered in 1999 inside an abandoned mine in Southern Spain, Pulpí Geode is the largest crystal 'cave' of its kind in the world. But what exactly is a geode and how do crystals form inside them?