The downside of the cave’s growing popularity: Increasing tourism has been great for the local economy, but it's believed to be disturbing the birds, so more restrictions have gradually been placed on would-be adventurers.
Xiaozhai Tiankeng is actually a sinkhole WITHIN another sinkhole
If a sinkhole ever does open up under your property, you can rest assured that it almost certainly won’t be as big as China’s Xiaozhai Tiankeng, the largest sinkhole on Earth.
What you’re seeing up there is actually a sinkhole in another even larger sinkhole, together making up a drop of around 662 m at the deepest.
It took more than 100,000 years for the elements to cut the hole this deep, and while nearby locals knew about it for centuries, it was “rediscovered” by surveyors in 1994.
Since then, of course, it’s a haven for tourists. If you look carefully at the pic above, you can just see the faint line of a staircase along the vertical wall of the lower sinkhole. It’s too far to see, but it’s made up of around 2,800 steps in total.
That’s an awful long way to walk, so if you like, you can take the shortcut, like these base jumpers:
The hole is so far across, they have to go along a cable to reach a point where they can drop directly into the lower sinkhole. And when that first jumper lets go of the cable around 30 seconds in, watch how much freefall time he has before he has to pull his chute. Looks to us like around 10 seconds.
And unlike Mexico’s Cave of Swallows, there’s no semi-toxic, bug-ridden guano pit waiting for him, but a thriving forest ecosystem, with more than 1,200 species of plant and rare animal species like the vulnerable clouded leopard.