Natural Wonder Blue Pond is located on the left bank of the Bieigawa River, southeast of Biei City in Hokkaido, Japan, about 2,5 km northwest of the Platinum Hot Springs at the foot of Mount Tokachi. The pond got its name because of the unnatural bright blue hue of the water. In combination with the stumps protruding above the surface of the water, the Blue Pond has a charming look.
The blue pond appeared on this place not so long ago. This is an artificial reservoir, and it was formed when a dam was erected to protect the area from mudflows sliding down Mount Tokachi. After the eruption in December 1988, the Hokkaido Regional Development Bureau decided to build a dam in the headwaters of the Bieigawa River. Now the water, closed by the dam, is collected in the forest, where the Blue Pond was formed.
The blue color of the water is completely inexplicable. Most likely, the presence of aluminum hydroxide in water contributes to the reflection of the blue spectrum of light, as occurs in the earth’s atmosphere. The color of the pond changes during the day and even depends on the angle at which a person looks at it. Although the water looks blue from the shore, it is actually clear.
The scenic town of Biei has been a popular tourist destination for years, but the Blue Pond has made it the center of attention, especially after Apple included an aquamarine pool image in the recently released OS X Mountain Lion.