Lake Chūzenji 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 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, and the water reaches a depth of 163 m. The Yukawa River is the principal source of water. It drains through the Kegon Falls.
Chuzenji Lake was discovered in 782 by a priest named Shōdō when his group succeeded in climbing Mt. Nantai. Considered sacred, the mountain was closed to women, horses, and cows until 1872.
Coordinates 36°44'20.25" N 139°27'33.042" E