Lake Chuzenji (Chuzenji-ko) is a scenic lake in Nikko National Park in the city of Nikko. 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 km˛ 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.
Lake Chuzenji was discovered in 782 by a priest named Shodo when his group succeeded in climbing Mt. Nantai. Considered sacred, the mountain was closed to women, horses, and cows until 1872. In the middle of the Meiji-era and early Showa -era, many European embassies built vacation houses around the lake. The former Italian villa has been renewed and is now open to visitors. Other sites around the lake include Futara Shrine built in 790, Chuzenji Temple, and Kegon Falls. In spring, cherry blossoms are blooming. In summer, people can escape the heat and enjoy bird watching and hiking. In fall of course, there are the famous beautiful autumn leaves and in winter there is the Snow and Ice Festival, plus winter sports like skiing and skating.
The lake was a favourite summer haunt of Sir Ernest Satow when he was Britain's envoy in Japan, 1895-1900 as his diaries of that time attest. He constructed a house by the lake which is still owned and used to this day by the British Embassy.