Introduction to the Underwater World: The most amazing thing in Bailong Cave is a stone stalactite hall covering an area of ​​thousands of square meters - the Underwater World, also known as the best mirror in the world. Because there happens to be a pool of still water underground, the hundreds of thousands of stalactites on the top of the cave are clearly reflected in the water, like a mirage, both illusion and reality, and it is incredibly beautiful.