Introduction to Laangtso: Laangtso Lake, also known as Ghost Lake (also known as Rakshas), means "poisonous black lake" in Tibetan. It is located in Pulan County, Ngari Prefecture, with an altitude of 4574 meters, close to the holy water of fresh water. The lake is separated by a road and is a brackish water lake. Therefore, the water in the lake is not drinkable by humans and animals. This is probably the origin of the name "Ghost Lake". Laang Tso Ghost Lake is a close neighbor of the Holy Lake. The scenery is equally beautiful, and the lake water is also mesmerizingly blue, but it is labeled as a "ghost lake" and placed in another book. In fact, Holy Lake and Ghost Lake were originally one lake. Due to climate change, the lake shrank and the water level dropped, so they were separated by a narrow hill. Local people believe that the bottoms of the two lakes are connected. If one day the water of the Holy Lake flows into the Ghost Lake along the river channel, and gold fish and blue fish flow into it at the same time, the water of the Ghost Lake will become as sweet as the water of the Holy Lake.