Wudalianchi Crystal Palace lava tunnel attraction Wudalianchi Scenic Area Crystal Palace, this is the real witness to the miracle, there are many underground caves in the country, but lava tunnels are rare in China. Crystal Palace is an underground cavern landscape formed by volcanic eruptions. It is 150 meters long. The ice in the cave is not changed all the year round. It is warm in winter and cool in summer, and the most amazing thing is ice flower. There are various kinds of ice. The ice sculpture landscape is very beautiful under the light.