池 Travel and Tourism Tips
Umijigoku
It is the largest in Beppu Jigoku and features a cobalt blue pond. Umi Jigoku got its name because the color of the pond looks blue like the sea. T...
Shirogane Blue Pond Biei
The secret to the blue color of Blue Pond is the aluminum ions contained in the water. Aluminum ions absorb and reflect blue light from sunlight, whic...