Introduction to Long Lake: Entering the mouth of the Black Dragon Pool Canyon is the artificial lake - Long Lake. The canyon here is wide and the river bed is flat. Not far from Long Lake, there are two mud-rock dams several meters high, which block the Wuzhi River in the middle, blocking the water from flowing out and flowing back into the lake. When the rainy season comes, the water level will rise, overflowing the top of the dam, forming a waterfall, and flowing straight to the bottom of the dam.