The Taishan underground rift is a secret zone between the two mountains of Mt. Tai and Lushan. In 2003, the ground collapsed with 100 m in diameter and the geological change was so important that a nearby village was safely relocated.
Few years later, a farmer lost his drill while digging a well in his backyard and an official exploration started to check the underground situation.
The Baotailong Underground Rift Valley officially opened in April 2016. The size is so gigantic that it needs a 28-minute rafting to fully appreciate its beauty.
The rift is hundreds of meters deep and a rich groundwater resource in the cave provides the base to water-raft.
The Guinness World Records certified it as the longest unpowered underground river rafting.