Lake Onneto
Overview
Lake Onneto, in the westernmost region of the Akan-Mashu National Park, is located about 25 minutes by car from the Akankohan Eco-museum Center. The lake is believed to have formed when an eruption from Mt. Meakan blocked the flow of the upstream section of the Rawan River. The lake’s waters mysteriously seem to change color depending on the weather, viewpoint, and time of day.
Features of the Lake Water
In the Ainu language, Onneto means “old, large” (onne) and “lake” (to). The lake is the highest lake in Akan area at an altitude of 623 m. It is located on the west side of Mt. Meakan. Known as one of Hokkaido’s “Three Mysterious Lakes,” on sunny days the lake appears as a mixture of cobalt blue and emerald green, dubbed Onneto Blue. The scenery is especially beautiful in fall due to the contrasting colors of the sky, mountains, and red leaves, all reflected in the blue-colored water. Lake Onneto’s unique hue is produced by a combination of the water’s transparency and mud that has accumulated on the lakebed. Additionally, the lake’s pH level has been changing from acidic to slightly alkaline over a long period of time; this is believed to be a natural phenomenon. Currently, the lake is close to pH-neutral, and algae and small fish not previously seen in the colorful waters have begun to appear.
Activities
A fifty-minute walking trail around the western side of the lake begins at Meakan Onsen and ends at the Onneto Campground. Along the trail, animals such as black woodpeckers and Siberian chipmunks can be seen. The Onneto Campground, nestled in the tranquil forest on the south side of the lake, is open from June to October. In order to protect Lake Onneto, canoeing and other water sports are not allowed.
