I am watching the ice lamp in the summer. The caves in many places have been visited. The Crystal Palace in Wudalianchi is the most special. There is island-like permafrost in the Wudalianchi area, which causes the rocks in the cave to be cooled, thus forming an ice cave. In the northeast, it is not surprising to look at ice and snow in winter, but it is a miracle to be able to experience the "winter in the summer." The four strange four geeks of Wudalianchi "three volts for ice and snow" refer to this place.