Lake Tazawa, a dozen km north of Kakunodate, is Japan's deepest lake (423 metres / 1388 feet). The lake is an almost perfect circle of 20 km of circumference.
Tazawa-ko is noted for the clarity of its water (2nd clearest in Japan) and is a popular place to practice watersports.
Mount Komaga-take 駒ケ岳
The 1,637m tall Mt Komagatake stands on the eastern edge of Lake Tazawa. Although it is not one of Japan's most scenic elevation, its alpine flora and refreshing temperature in summer make it a pleasant trek.
There are several lower peaks around and the neighouring Mt Nyuto-san is famous for its Nyūtō-onsen hotspring.
How to get there
The JR take a bit less than 3 hours to Tazawa-ko station from Tokyo station by shinkansen (￥8,720), and an additional 15 minutes by bus from there to the shore of the lake at Tazawa-kohan.
From Kakunodate Tazawa-ko is only 13 minutes by shinkansen (￥320), which cost exactly the same as the slower JR Tazawa-ko line (20min).
To reach Komagatake, the easiest is to take a bus (about 50min, ￥800) from Tazawa-ko station to Komagatake's eight station (駒ケ岳八号目) and start climbing from there (about 1 hour to the summit).