Introduction to Yanni Cave: Yanni Cave is located under Tianlong Peak, also known as Haiyan Cave. The entrance of the cave is in the shape of a swallow's mouth and faces the southwest. The cave as a whole runs north-south. The cave is more than 120 meters deep and the highest point of the cave roof reaches more than 30 meters. The interior is divided into two halls, front and rear, connected by a three-meter-wide secret passage. The four walls of the cave are convex and concave. There is a stalagmite with a thick upper part and a sharp lower part rising from the ground in the back hall. There is a curved stalactite hanging above the center of the hall. The inner hall is to the right. There is a winding underground secret passage below. According to the legend of the older generation of local people, someone brought a black dog into this secret passage and came out from a cave at the foot of Yashan Mountain the next day.