Tianchi, also known as the Heavenly Lake, is an absolute must-visit location of Changbai Mountain. It is settled atop the mountain, at an altitude of 2,189 meters above sea level. The area where the lake is set is a crater formed through multiple eruptions 12 million years ago, the last of which being recorded in 1702. Fortunately, the volcano has since remained dormant. With overflowing springs and the collection of rainwater, Tianchi, a vast alpine lake of more than ten square kilometers, gradually formed, and is now the grandest in China. It is like a beautiful piece of jade embedded among the mountain clusters. It is usually a brilliant blue that reflects the beautiful sky and passing clouds. From mid-October to mid-June, it is typically covered in a blanket of flat white ice and snow.