Pagsom Co is also known as Gongga Lake. It means "three rocks" in Tibetan. Located in Gongbo'gyamda County, it is a sacred lake of the Nyingma Branch of Tibetan Buddhism. The shape of Pagsom Co is like a crescent embedded in the deep valley. The water is clear, reflecting the surrounding snowy mountains and primordial forests. The Tsozong Gongba Monastery stands on Tashi Island and was built during the late Tang Dynasty. The reefs on the island are carved into images of animals and Buddha statues. Tsozong Gongba Monastery is a two-story structure of earth and wooden materials. The three statues, Chenresig, Guru Rimpoché and Sakya Thukpa, are worshiped here.