Introduction to Mystery Cave No. 4: Mystery Cave No. 4 is the largest one in the project. The entrance is a platform, with a steep stone wall on the right and stone steps going down the wall on the left. The first few caves are as jagged as the enigmatic caves. The original steps are three meters long, the depth from the entrance to the bottom of the cave is more than 20 meters, and the steps are more than 50 meters long. The bottom of the cave is relatively flat, with an area of ​​about 2,000 square meters. The rectangular square pool is also several times larger than the previous caves.