Lake Chuzenji is the largest lake in Tochigi, framed by 25 kilometres of incredible nature. The area used to be a popular summer resort for foreigners.
Created by an eruption of Mt. Nantai, Chuzenji lake is a symbol of Nikko.
You might get the Chuzenji Onsen Bus Free Pass at 2,000 yen at the station for free stop-overs at Chuzenji Lake (中禅寺湖) and Kegon Falls (華厳の滝).
You can also join in a Sightseeing cruises to view the area and get around. Cruises depart from the pier in Chuzenjiko Onsen and range from ten minute shuttles across the lake to Chuzenji Temple (160 yen) to 60 minute round courses (1250 yen).
Take a jacket as it can be quite cool at the lake being so high!
In popular season, the bus route gets very crowded, so you might go to Chuzenji area first in the morning and see Toshogu and other fine temple/shrines afterwards.