Giant karst sinkhole cluster found in Guangxi

"The biggest one we have discovered is over 300 meters in depth and can be listed among the world's 50 largest karst sinkholes. We spent two days descending to reach the bottom," said Chen Lixin, leader of the Chinese experts.

Situated on the top of a 700-meter-high mountain, the entrance of the sinkhole was covered with a dense forest. Only a drone in the air could capture a glimpse of it.