We made a quick trip to my father's birthplace called Kumamoto during our trip to Japan recently. Kumamoto is located on the southern island of Japan. It is famous for many things, and Mount Aso is definitely one of them.
Mount Aso is the largest active volcano in Japan, which rises to 1592 m above sea level. There are several craters, holes formed by various eruptions. You can go up to see one of the craters by car.
It was very windy that day, but we managed to peek into the crator. It had a pool of water of a beautiful emerald green color, which was pretty much covered by steam coming from the water most of the time. I heard the the temparature of the water is around 50-60 centigrade, which is quite a bit hotter than the normal Japanese bath. The water is heated by the volcano gas. The fact that it has a pool of water seemed to mean that the volcano is very active, and when the water changes its color to black, the eruption occurs in the crator.
Aso weather is pretty unique, as it got nice when you go down the mountain but it was very windy, cloudy, and foggy as we went up. Here is the photo of a very cozy family of "red cows."