The Xiaozhai Tiankeng, also known as the Heavenly Pit, is the world's deepest sinkhole.

It is located in Fengjie County of Chongqing Municipality. The Xiaozhai Tiankeng is 626 meters (2,054 ft) long, 537 meters (1,762 ft) wide, and between 511 and 662 meters (1,677–2,172 ft) deep, with vertical walls. Its volume is 119,349,000 m³ and the area of its opening is 274,000 m². 

This material has been dissolved and carried away by the river. The sinkhole is a doubly nested structure—the upper bowl is 320 meters (1,050 ft) deep, the lower bowl is 342 meters (1,122 ft) deep, and the two bowls are on average 257 to 268 m (843–879 ft) across. 

Between both these steps is a sloping ledge, formed due to soil trapped in the limestone. In the rainy season, a waterfall can be seen at the mouth of the sinkhole.

According to en.wikipedia