The headquarters of the People's Committee of Ta Phin commune, about 1 km north of the limestone mountains, is a branch of the Hoang Lien Son range. In this mountain range there is a small mountain, at the foot of the mountain, which opens into a cave at the bottom of the mountain, about 5 meters wide and about 3 meters wide. Go about 30 meters in the dark, bumpy will encounter a cave. From here, many of us go to the bottom of the earth just as a person goes through, many cliffs have to cling to the rock, rocking people up. Follow these small walls as it radiates out into many ways, even hitchhiking, scattering and eventually returning to its original location.