The lava of eruption of the Mt. Mitsudake made landscape of Lake Yunoko. Altitude of the lake is 1478m. The circumference is 3km, and it takes you about 1 hour to go round.

There are broadleaf trees such as Noriutsugi (Panicled hydrangea), Ohkamenoki (Viburnum furcatum), Udaikamba (Monarch birch). In addition to that, there is the natural forest of conifer such as Kometsuga (Northern Japanese hemlock) and Nikko fir. Also, the Azumashakunage grows gregariously on the southern shore near the Yudaki waterfall. You can enjoy watching flower in May and June. Also, there is the peninsula called Usagijima, and is marsh there. Cottonsedge and American cranberry grow there.

In addition, there are many wild birds around the Lake Yunoko. Mallard, Tufred Duck, Smew and Wigeon are seen in the winter.