Mapam Yumco Lake (or Lake Manasarovar) lies 20 km southeast of Mt Kailash and is north to Namnani Peak, approximately 800 kilometres (500 mi) from Lhasa, the administrative capital of Tibet Autonomous Region. Storing 20 billion cubic meters of fresh water, it is the highest freshwater lake in the world. At an elevation of 4,583 meters, the lake covers an area of 412 sq. km, the deepest point of the lake is over 70 meters.

In the Tibetan language, "Mapam" means "invincible" while "Yumco" refers to "jade lake." In his works "Records of Western Regions in Great Tang," monk Xuanzang (600-664) of the Tang Dynasty (618-907) referred to Mapam Yumco as the sacred Yaochi Lake of Nirvana.

Mapam Yumco enjoys a reputation equal to the holy mountain. Mapam Yumco Lake once appeared in many religious records and legends. Indian legend claims it to be a place where Siva and his wife Goddess Woma, daughter of the Himalayas, bathed. Tibetan legend claims it to be where the God Guangcanlong lived. In Buddhist scriptures, the lake is named the "mother of the rivers in the world".

In Tibetan Buddhism, it is believed that bathing with the water of Mapam Yumco will drive off avaricious desires, troubled thoughts and past sins; drinking the lake's water will keep one healthy and away from disease; while circling the lake will bring boundless beneficence to the pilgrims. Thus all the pilgrims to Tibet will come to Mapam Yumco and regard circling and drinking from the lake as their greatest fortune. As a result, the holy lake is crowded with people who come to take a bath every year. These people also carry samples of water from the holy lake back home for their relatives and friends.

Every summer, flocks of swans will gather on the lake, bring grace and life to the area. Legend says that the fish in the lake can cure sterility, dystopia, dropsy and other illness. Chemical analyses show that the lake water indeed contains various types of minerals.

At just 3 kilometers away from Mapam Yumco, the "Ghost Lake" La'ang is a salt lake. With high winds and rapid currents, it is difficult for fish or weeds to grow.