With high carbon dioxide, low oxygen and no photosynthesis, here’s how an entire ecosystem persists in Movile Cave, one of the most extreme environments on Earth.

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 ...

In 2001 a team led by Ukrainian Yuri Kasjan set a world record in the cave of 1,710 meters (5,610 ... Denis Kurta and Dmitry Fedotov squeezed through a narrow, 100-meter-long (328-foot-long ...

Here’s everything that makes this cave a ... [+] world of its own. Some of Earth’s most extreme frontiers lie beneath our feet, in places so inhospitable they might as well belong to another ...

The narrow paths flowed up and down. The group spent four days wading through hip-high waters before traversing through and camping in soaring caves. At the end of Hang Son Doong stood the Great ...