Lake Okotanpe is a small lake with circumference of 5 km, located in the west of Chitose City, Hokkaido. It is a dammed lake created by lava that blocked the Okotanpe River, which flows out of this lake into Lake Shikotsu. The lake is located in a relatively high land with an altitude of the lake surface of 574 m. The lake is surrounded by the primary forest of Jezo spruce and Sakhalin fir, which create serene hush. Lake Okotanpe, together with Lake Shinonome and Lake Onneto, is counted as one of the 3 mysterious lakes in Hokkaido. The hue of the lake surface varies delicately with seasons or weather. As the lake itself and the surrounding area are designated as a special protection area, visitors cannot go down to the lakeside. However, the lake seen from the nearby observation tower is an exquisite view. If you look down at the mysterious change in color from cobalt blue to emerald green on the surface of the lake, which is surrounded by the huge primary forest spreading at the foot of grand Mt. Eniwa, you will be convinced it’s a really mysterious lake. You can enjoy marvelous changes in nature.