Introduction to Longtan Lake: Located under the plank road at the first pass of Longtan Grand Canyon, it is about tens of meters long and only 3 to 5 meters wide. It has two steep walls. Spring water gushes out from the top of the right wall all year round. Like a green dragon spitting saliva, a series of large and small beads dripped into the lake like a jade plate, causing ripples to scatter in all directions.