Shirogane Blue Pond Biei (Aoi-ike)

Category: Mineral Pond & Volcanic Wonder | Location: Shirogane, Biei-cho, Kamikawa-gun, Hokkaido 071-0235

Tucked within serene white birch forests southeast of Biei, the Shirogane Blue Pond (*Shirogane Aoi-ike*) is a mesmerizing accident of nature and engineering. Following the devastating December 1988 eruption of Mount Tokachidake, regional authorities constructed concrete erosion control dams along the Biei River to intercept potential volcanic mudflows. Thermal spring runoff collected behind one of these concrete barriers in the forest, submerging native Japanese larch trees and creating an otherworldly pool of luminous, turquoise-cobalt water. The pond’s surreal color is caused by Rayleigh scattering: thermal spring water rich in colloidal aluminum hydroxide surges from subterranean fissures at nearby Shirahige Waterfall and mingles with the fresh currents of the Biei River. These microscopic suspended mineral particles scatter short-wavelength blue light, creating an intense azure glow. In 2012, Hokkaido photographer Kent Shiraishi captured the haunting silhouette of withered, silver-limbed larch trees standing above the calm blue mirror beneath a fresh snowfall, an image that Apple selected as an official master wallpaper for OS X Mountain Lion. The pond’s colors evolve through the seasons—from intense cobalt blue on clear summer mornings to emerald-turquoise framed by golden autumn foliage. In winter, the pond freezes into a blanket of virgin snow and hosts an ethereal LED illumination show every evening from November through April. Just 5 minutes further uphill stands Shirahige Waterfall, where groundwater cascades 30 meters through cliff fissures into the cobalt "Blue River." Equipped with boardwalks and parking facilities, the pond is a 20-minute bus ride from JR Biei Station.