Photo taken on May 25, 2016 show the Luoquanyan sinkhole in Xuan'en County, Central China’s Hubei Province. The sinkhole, naturally formed as a result of karst processes, is 290 meters deep and its interior can only be reached by rope descending. The pit lies near an underground karst cave that extends three kilometers. Both the pit and surrounding caves are local tourist attractions. (Photo/Xinhua)
