Changbai mountain pool in the sky is a dormant volcano. The crater forms water into lakes. Xiaring pool water is bluer than the sky. Winter frozen ice snow is white and surrounded by 16 mountain peaks. There is a narrow pool of water overflowing between the peaks and the Longmen Peak, and it is a source of the Songhua River.
Changbai Mountain was formed 12 million years ago in a geological orogeny. After many eruptions, it has become a giant umbrella body. When the volcano is dormant, springs overflow and form a vast area of more than ten square kilometers. Tianchi is 2189.1 meters above sea level, slightly elliptical, 4.4 kilometers long from north to south, and 3.37 kilometers wide from east to west. The catchment area is 21.4km2, the water surface area is 9.82km2, the water surface perimeter is 13.1 kilometers, the average water depth is 204 meters, and the deepest point is 373 meters. The total water storage capacity is 2.04 billion cubic meters. Tianchi water temperature is 0.7°C-11°C and the annual average temperature is 7.3°C. Tianchi is like a magnificent jasper embedded in the majestic peaks of Changbai Mountain. It is the largest volcanic lake in China and the deepest mountain lake in the world. It is now the boundary lake between China and North Korea.