Lake Yamanaka is located in the village of Yamanakako in Yamanashi Prefecture near Mount Fuji, Japan.
It is the largest of the Fuji Five Lakes in terms of surface area, and is the highest of the Fuji Five Lakes in terms of elevation. It is also the third highest lake in Japan, with a mean surface altitude of 980.5 metres. Conversely, the lake is also the shallowest of the Fuji Five Lakes, with a maximum water depth of only 13.5 metres. The lake, which was formed by lava flows from an ancient eruption of Mount Fuji, is drained by the Sagami River, and it is the only of the Fuji Five Lakes to have a natural outflow.Carp, dace and smelt were introduced to the lake in the Meiji period, although early efforts to introduce sockeye salmon were not successful. In more recent years, introduced exotics such as black bass and bluegill have increasingly displaced native species. In terms of plant life, a variety of marimo was discovered in the lake in 1956.
Wikipedia https://en.wikipedia.org/wiki/Lake_Yamanaka
Coordinates 35°25'8.031" N 138°52'27.848" E