![An aerial photo shows a waterfall in Didonghe Tiankeng, a giant karst sinkhole at Huoshizi Village of Ningqiang County in Hanzhong, northwest China\'s Shaanxi Province. With a maximum depth of 340 meters, the Didonghe Tiankeng is the largest in Chanjiayan Tiankeng Group in Ningqiang County. (Photo/Xinhua)](http://www.ecns.cn/hd/2019/05/20/2fd6af354ad6455b96ea1cfd9a9c1908.jpg)
An aerial photo shows a waterfall in Didonghe Tiankeng, a giant karst sinkhole at Huoshizi Village of Ningqiang County in Hanzhong, northwest China's Shaanxi Province. With a maximum depth of 340 meters, the Didonghe Tiankeng is the largest in Chanjiayan Tiankeng Group in Ningqiang County. (Photo/Xinhua)
![An aerial photo shows a waterfall in Didonghe Tiankeng, a giant karst sinkhole at Huoshizi Village of Ningqiang County in Hanzhong, northwest China\'s Shaanxi Province. With a maximum depth of 340 meters, the Didonghe Tiankeng is the largest in Chanjiayan Tiankeng Group in Ningqiang County. (Photo/Xinhua)](http://www.ecns.cn/hd/2019/05/20/bc9446872b1f46678c80b81767efdb09.jpg)
An aerial photo shows a waterfall in Didonghe Tiankeng, a giant karst sinkhole at Huoshizi Village of Ningqiang County in Hanzhong, northwest China's Shaanxi Province. With a maximum depth of 340 meters, the Didonghe Tiankeng is the largest in Chanjiayan Tiankeng Group in Ningqiang County. (Photo/Xinhua)
![With a maximum depth of 340 meters, the Didonghe Tiankeng is the largest in Chanjiayan Tiankeng Group in Ningqiang County. (Photo/Xinhua)](http://www.ecns.cn/hd/2019/05/20/1735341f26b847bba4df36f0326e6461.jpg)
With a maximum depth of 340 meters, the Didonghe Tiankeng is the largest in Chanjiayan Tiankeng Group in Ningqiang County. (Photo/Xinhua)
![An aerial photo shows a waterfall in Didonghe Tiankeng, a giant karst sinkhole at Huoshizi Village of Ningqiang County in Hanzhong, northwest China\'s Shaanxi Province. With a maximum depth of 340 meters, the Didonghe Tiankeng is the largest in Chanjiayan Tiankeng Group in Ningqiang County. (Photo/Xinhua)](http://www.ecns.cn/hd/2019/05/20/cd9da16d0b8143729b9f5eca2994df7a.jpg)
An aerial photo shows a waterfall in Didonghe Tiankeng, a giant karst sinkhole at Huoshizi Village of Ningqiang County in Hanzhong, northwest China's Shaanxi Province. With a maximum depth of 340 meters, the Didonghe Tiankeng is the largest in Chanjiayan Tiankeng Group in Ningqiang County. (Photo/Xinhua)
![With a maximum depth of 340 meters, the Didonghe Tiankeng is the largest in Chanjiayan Tiankeng Group in Ningqiang County. (Photo/Xinhua)](http://www.ecns.cn/hd/2019/05/20/290d06803c9a4183830350d1f7630188.jpg)
With a maximum depth of 340 meters, the Didonghe Tiankeng is the largest in Chanjiayan Tiankeng Group in Ningqiang County. (Photo/Xinhua)
![With a maximum depth of 340 meters, the Didonghe Tiankeng is the largest in Chanjiayan Tiankeng Group in Ningqiang County. (Photo/Xinhua)](http://www.ecns.cn/hd/2019/05/20/d66aa34d520f4840b20b13dee83dd91c.jpg)
With a maximum depth of 340 meters, the Didonghe Tiankeng is the largest in Chanjiayan Tiankeng Group in Ningqiang County. (Photo/Xinhua)