Name Biei wear and a small town at the foot of mount Tokachi, and located near a small pond that attracts tourists from all over the world for its unusual ultramarine green water. "Blue" pond Biei is located on the left Bank of the river Biegala on the island of Hokkaido.

It is remarkable, but this pond is not natural but artificial. After the eruption of Tokachi in 1988 increased the danger of vanishing from the slopes of the mountains of mud flow in the direction of the city. It was therefore decided to build a dam, which opened in the next year. After its construction in the forest began to accumulate water, and so formed a pond. His appearance did not cause any issues, but the causes of the unusual color of the water, also able to change colour, remain a mystery for the past quarter of a century.

Scientists are trying to explain this unique phenomenon, and according to one version, the unusual color is the result of mixing of water from thermal springs located nearby, with river water that is saturated with the hydroxide of aluminum. Due to the impurities, the water in the pond reflects the sunlight and at different hours when the rays of the sun fall on the water at different angles, takes on different shades – from bright turquoise to greenish-gray.

Mystery pond and add the trunks of birches and larches that stick out of the water over the entire area of the reservoir. The small size of the pond – it is possible to walk just half an hour. However, it attracts many photographers to catch in the lens changeable color of the water.

The popularity of the pond in Biei increased after in 2012, Apple posted his picture, taken by photographer Kent, Shiraishi, in its new operating system OS X Mountain Lion. On this picture, on the shore of the pond.) went the first snow. In winter, the pond is no less attractive, because through the thin crust of ice translucent turquoise color of the water, sticking out of the water and the trees spangled with snow flakes.