Located in the southeastern part of Jilin Province, China, Changbai Mountain is a volcano that has erupted multiple times. The crater has formed the famous Tianchi Lake, which sits at an elevation of 2,194 meters, covers an area of 9 square kilometers, and reaches a depth of 373 meters. Despite the harsh natural environment, scientists believe that large creatures cannot exist in the lake, yet local legends about the Tianchi Monster persist.

In August 1962, two creatures were reportedly spotted swimming in Tianchi by someone using a telescope. Again in August 1980, writer Lei Jia and others witnessed a similar phenomenon. They described the monster as having a head the size of a cow, with a neck longer than one meter and a chest protruding above the water, covered in dark brown fur with a white ring pattern. These descriptions sparked widespread discussion and speculation. Some argue that the existence of the Tianchi Monster is difficult to explain, given that the lake was formed relatively recently and lacks a food chain for large animals. Others believe that the so-called monster may simply be rocks or floating debris in the water, resulting in a visual illusion.