China's Tiankeng: The World's Largest Sinkholes and the Hidden Caves Beneath Them
Most travelers come to China for the Great Wall, the pandas, and the neon skylines. But hidden in the limestone heart of the southwest is a wonder that makes those landmarks look modest: the tiankeng (天坑), or "heavenly pit." These are not ordinary sinkholes but giant karst collapse pits more than 100 meters deep and wide — big enough to swallow a skyscraper.
China holds the overwhelming majority of the world's documented tiankeng, and the largest of them all sit within a day's drive of Chongqing. This guide explains what they are, how they formed, and how to see them without special gear.
What Exactly Is a Tiankeng?
The word was coined by Chinese speleologists only in 2001, at an international karst symposium in Beijing, to name a specific class of giant sinkhole. The strict definition has three requirements:
- Depth and width both exceed 100 meters. A smaller depression is just a doline or collapse pit.
- Vertical or near-vertical walls plunging to a rubble floor or, often, into a living cave system.
- A surface opening connected to underground rivers and gallery caves below.
By this definition the planet has only a few dozen true tiankeng — and China contains roughly 80% of them, clustered across Chongqing, Guangxi, Guizhou, and Sichuan.
The World's Largest: Xiaozhai Tiankeng
The giant of giants is Xiaozhai Tiankeng (小寨天坑) in Fengjie County, Chongqing. Discovered by modern science in 1994, its measurements are almost absurd:
- Depth: 662 meters from rim to floor — deeper than the Eiffel Tower is tall.
- Diameter: about 626 meters at the top, narrowing then widening into a massive underground chamber.
- Volume: an estimated 119 million cubic meters of open space.
Geologists believe it formed when the subterranean Qingjiang River dissolved the Permian limestone beneath the surface over millions of years until the roof collapsed. At the bottom sits a primeval forest and a cave network that drains toward the Three Gorges region.
The Dashiwei Cluster: Thirty Pits in One Valley
If one sinkhole is impressive, try thirty. The Dashiwei Tiankeng Group (大石围天坑群) in Leye County, Guangxi, packs more than 30 tiankeng into a single 20-square-kilometer area. The largest, Dashiwei itself, drops 613 meters with a floor covered in a virgin cloud forest that has evolved in near-isolation. Botanists have catalogued rare tree ferns and endemic species found almost nowhere else on Earth. The pits also connect to the Maze River Cave System, one of the longest in China.
Asia's Longest Cave: Shuanghe
Just north in Suiyang County, Guizhou, lies Shuanghe Cave (双河洞), the longest cave in Asia and among the top ten longest on the planet. Surveyed at over 409 kilometers, it contains eight vertical levels, frozen waterfalls of calcite, and fossils of extinct giant pandas. Its entrance sits at the bottom of a shallow karst valley — a reminder that every tiankeng is really just the skylight of a much larger hidden world.
Where to Actually Go
Not every tiankeng requires ropes. China has developed several into accessible destinations:
| Site | Location | Difficulty | Highlight | |------|----------|-----------|-----------| | Wulong Karst | Chongqing | Easy | UNESCO site, elevators to the pit floor | | Xiaozhai Tiankeng | Fengjie, Chongqing | Moderate | World's largest, hiking to the rim | | Dashiwei Tiankeng | Leye, Guangxi | Guided only | Virgin forest, vertiginous overlook | | Shuanghe Cave | Suiyang, Guizhou | Easy–Moderate | Walkable lit galleries |
The Wulong Karst (武隆喀斯特) near Chongqing is the most tourist-friendly: reachable by train or flight from the city, then a bus to elevators that descend toward the pit floor with viewing platforms over the chasm. It is a UNESCO World Heritage Site (2007) within the South China Karst.
Planning Your Tiankeng Trip
- Best season: April through October. Springs and early autumns give the clearest light; avoid the July–August peak travel weeks if you dislike crowds.
- Getting there: Base in Chongqing for Wulong and Xiaozhai (high-speed rail + bus), Baise for Leye, and Zunyi for Suiyang — all on major HSR lines.
- Guides: Dashiwei and any cave entry require licensed local guides. Unpermitted descent is illegal and dangerous.
- What to bring: sturdy shoes, a headlamp even for "lit" caves, and a rain jacket — karst weather turns fast.
Why They Matter
Tiankeng are more than photo backdrops. Their isolated micro-climates preserve species and climate records, and their cave systems are natural laboratories for carbon cycling. Chinese geologists now lead the world in tiankeng survey science, and new pits keep turning up — a 2022 expedition in Chongqing's Nanchuan district revealed a pit over 900 meters deep that had been hiding in plain sight. For the traveler, the appeal is simpler: standing at the rim of a 600-meter hole rewires your sense of scale in a way no skyline ever could.