Fengjie County, in the Chongqing Municipality, is where you'll find Xiaozhai Tiankeng, the world's largest and deepest ...

with hidden caves and tunnels believed to be inside The heavenly pits are some of the largest sinkholes in the world — in particular Xiaozhai Tiankeng, located in Fengjie County in southern ...

The Xiaozhai Tiankeng sinkhole is vast. Probably formed centuries ago by collapsing caves and underground rivers, teams of explorers have sought to understand its many mysteries for years.

When the weakened surface collapses into the cavern, it creates a sinkhole. They vary in size, from very small to the huge one seen at Xiaozhai Tiankeng in China, known as the Xiaozhai Heavenly Pit.