Photo taken on May 25, 2016 shows a 290-meter-deep karst cave in Luoquanyan Village of Xuan'en County, central China's Hubei Province.(Xinhua/Song Wen)
Photo taken on May 25, 2016 shows a 290-meter-deep karst cave in Luoquanyan Village of Xuan'en County, central China's Hubei Province.(Xinhua/Song Wen)