The photo shows Yanzidong Tiankeng (an area of naturally formed pits) in Napo County, south China's Guangxi Zhuang Autonomous Region, May 3, 2019.

NAPO, Nov. 17, 2019 (Xinhua) -- The newly discovered Tiankeng group, consisting of 19 Tiankeng, are mainly distributed in Chengxiang Township and Longhe Township in Napo County.

Most of the pit volume of Napo Tiankeng group is more than one million cubic meters and the original landscape is well preserved.

China's Tiankeng are mainly found in Guangxi, Guizhou, Chongqing, Yunnan, Sichuan and Shaanxi.

A cave expedition member prepares equipment before exploring Tiankeng (an area of naturally formed pits) in Napo County, south China's Guangxi Zhuang Autonomous Region, Nov. 2, 2019.

A cave expedition member works in a cave connecting Jiayang Tiankeng (an area of naturally formed pits) in Napo County, south China's Guangxi Zhuang Autonomous Region, Nov. 3, 2019.

A cave expedition member stands among trees at the bottom of Nongyang Tiankeng (an area of naturally formed pits) in Napo County, south China's Guangxi Zhuang Autonomous Region, Nov. 2, 2019.

Cave expedition members rest at the bottom of a Tiankeng (an area of naturally formed pits) in Napo County, south China's Guangxi Zhuang Autonomous Region, Nov. 2, 2019.

The photo shows the scene at the bottom of Nongyang Tiankeng (an area of naturally formed pits) in Napo County, south China's Guangxi Zhuang Autonomous Region, Nov. 2, 2019.

A cave expedition member works in a cave in Napo County, south China's Guangxi Zhuang Autonomous Region, Nov. 5, 2019.