Shirogane Blue Pond (Aoiike)

Biei Shirogane is an artificial lake formed where water collected behind the Tokachidake volcanic sabo levee. Colloidal aluminum hydroxide particles from mixed upstream hot spring water and river water reflect sunlight, so the water shifts between emerald green and cobalt blue. A walking path follows the dead trees in the lake and the reflections of the forest, and the site is not large so viewing does not take long. In seasons when snow accumulates, the color of the lake water is difficult to see.