Lake Haruna榛名湖[ Haruna ko ]

Lake Haruna (榛名湖, Haruna-ko) is a caldera lake. It lies near the summit of Mount Haruna, within the city limits of Takasaki, Gunma Prefecture, Japan. A former name for the lake is Lake Ikaho (伊香保沼, Ikaho-numa). In the summer, the lake is a popular destination for campers. The surface freezes in the winter, and it affords skating and ice fishing for wakasagi.

from Lake_Haruna (Wikipedia) CC BY SA 3.0