A high-altitude lake about 8 km north of Kedarnath at 4,135 m, named for the serpent king Vasuki who, according to mythology, takes a ritual bath here. The trek is steep and rough, gaining nearly 600 m of altitude with several stream crossings.
The reward is one of the loveliest spots in the Garhwal Himalayas: a clear blue lake reflecting the surrounding peaks, with the imposing 6,940-metre Chaukhamba massif rising directly behind. Allow a full day; a guide and warm clothing are essential. Best in September and October when the monsoon has cleared.