A jungle inside a cave? A roof collapse long ago in Hang ... Stands of bamboo and other vegetation cover mounds of limestone here, making the place all but impenetrable. Below the surface, this ...

Keoni Alvarez, a 31-year-old activist and filmmaker who has battled developers trying to build atop burial caves, says that whenever human remains are found inside a lava tube, they render the ...

Hang Son Doong is the world's largest known cave, with enough space in some of its passages to fly a Boeing 747 airplane ...

You can tell roughly how old they are by their size. They grow about 10cm every 1000 years. The stalactites and stalagmites make these really dramatic limestone features inside caves. Look!

"If you get lost inside, you may never be able to find ... to India's longest general cave - the 31.1km-long Liat Prah limestone cave system. Many of them are huge, and carry deep rivers.

They left behind petroglyphs, which you can still see today on the marine coral limestone walls ... photos are only permitted in one area inside the caves, although you're given plenty of time ...

More than 100 metres (328ft) beneath them is a lost world of ancient forests, plants and animals. All they can see is leafy ...