Introduction to Yuyue Skylight: There is an underground river in Wuxi Lake connected to the end of Longfeng Lake. This underground river is 668 meters long in total. There is also a hole in the mountain that connects to the river. When the water level is shallow, it can be supported from the hole. The boat enters the underground river. When the water level is high, there are fish in the river going between the two lakes. The fish swimming under the cave from the underground river jump into the air because they suddenly see the light. The locals call this scene "fish jumping through the skylight".