Lake Onneto

Lake Onneto is a part of the Akan Mashu National Park in eastern Hokkaido. It was created due to the eruption of Mount Meakan, after its lava flow stopped the flow of a river.
The lake is highly acidic, and there are no fish in the lake. You can find non-fish creatures such as crayfish. However, the acidity causes the lake to have a beautiful, vivid blue color.
Nearby, there is an observation deck and a walking path from where you can get a great view of Lake Onneto. In the area, there are also a few hot spring facilities.
The area is closed off between December and April due to the heavy snowfall.