Arxan Tianchi (Heavenly Lake)

Arxan Tianchi

Arxan Tianchi is situated on Tianchiling Mountain, 74 kilometers northeast of Arxan City. It was formed when volcanic ejecta accumulated around the crater, creating a circular wall with a central depression that filled with water over the years. At an elevation of 1,332.3 meters, it is lower than both the Tianchi of Changbai Mountain in Jilin Province and the Tianchi of Tianshan Mountain in Xinjiang, ranking as the third highest in China. Tianchi is a high-altitude volcanic crater lake, formed by water accumulation after a volcanic eruption.

Climbing to the top of Tianchi Mountain doesn’t offer the feeling of “looking down upon all the other mountains”—on the contrary, the view feels more confined, with only the 13.5-hectare lake surface and the corresponding patch of sky in sight. Locals from the nearby forest farm say, “The depth of Tianchi is unfathomable, and tourists are not allowed to boat or swim in it. They once conducted surveys by tying weights to the end of measuring ropes and lowering them into the lake—after more than 300 meters, they still hadn’t reached the bottom. They also released fish fry into the lake, but none survived. Later, they put lively crucian carp into the lake, but these fish quickly disappeared without a trace—no fish were seen jumping, and no dead fish floated to the surface. Tianchi has many mysterious aspects. One is that it neither dries up during long droughts nor overflows during heavy rains, and its water level remains stable for years. Another is that there are no rivers flowing into or out of Tianchi, yet the water remains incredibly clear. A third mystery is that while the nearby Sister Lakes, just a few miles away, are abundant with fish, Tianchi has none. The fourth is its unfathomable depth—some humorously say that Tianchi is connected to the Earth’s core.”