1. In Antu County, Yanbian Korean Autonomous Prefecture, Jilin Province, Changbai Mountain Tianchi is a dormant volcano. The crater is flooded, and the water in the Xiarong Pool is bluer than the sky. Winter is as white as snow, surrounded by 16 peaks. There is only a narrow channel between Tianhuo Peak and Longmen Peak flowing into Changbai Waterfall, which is the source of Songhua River.
2. Changbai Mountain was formed in the geological orogeny 12 million years ago. After many eruptions, it became a huge umbrella. When the volcano was dormant, the spring overflowed, forming a vast water surface of more than ten square kilometers. The Tianchi Lake 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 21.42, the water surface area is 9.822, the water surface perimeter is 13.1km, the average water depth is 204m, and the deepest point is 373m. The total water storage capacity is 2.04 billion cubic meters. The water temperature of Tianchi Lake is 0.7-11, and the annual average temperature is 7.3. Tianchi Lake, like a magnificent jasper inlaid between the majestic peaks of Changbai Mountain, is the largest volcanic lake in China and the deepest mountain lake in the world. Now it is the border lake between China and North Korea.