Turquoise blue
Shifting with the light.
LR0725 — CC BY-SA 4.0 · MaedaAkihiko — CC BY-SA 4.0 · Noriyoshi Emura — CC BY-SA 3.0 · taku-k — CC BY 3.0 · 肖红军 — CC BY-SA 3.0 · LR0725 — CC BY-SA 4.0 · Tomoki Nagahira — CC BY 3.0 · Calistemon — CC BY-SA 4.0
A strikingly turquoise pond near the town of Biei, created by works on the Biei River after the 1988 eruption of Mount Tokachi to protect the town from volcanic mudflows; water gathered and flooded part of the forest, leaving dead tree trunks standing in the water. The blue is thought to come from fine aluminium compounds suspended in the water, which reflect blue light, and the colour changes with the weather, the season and the time of day. Heavy rain can cloud it, as after a typhoon in 2016, when it briefly turned brown. In winter the pond freezes under snow and is lit up at night in the cold season. Close by, in the Shirogane hot-spring area, the Shirahige Falls pour into the blue Biei River. Seeing the pond is free; parking has cost 1,000 yen since 1 July 2026, and the car park opens 7:00-19:00 from May to October and 8:00-21:30 from November to April, according to the Biei tourist association. Buses run from Biei and Asahikawa stations.
Shifting with the light.
In the water.
Over the snow.
Shirogane, Biei
Fine aluminium compounds suspended in the water are thought to reflect blue light; the colour shifts with weather and season.