Lake Chūzenji (中禅寺湖, Chūzenji-ko) is a scenic lake in Nikkō National Park in the city of Nikkō, Tochigi Prefecture, Japan. It was created 20,000 years ago when Mount Nantai (2484 m) erupted and blocked the river
The lake has a surface area of 11.62 km² and a circumference of 25 km. Its elevation at the surface is 1,269 m (4,124 ft), and the water reaches a depth of 163 m (508 ft). The Yukawa is the principal source of water. It drains through the Kegon Falls.