Here is the town of Beppu, at the northeast of Kyushu:
The vapor comes from natural hot springs, extremely common in Japan and called onsens (温泉, which literally means "hot (温) spring(泉)"). They are so common that the Japanese have taken advantage of them to build public baths, also called onsens by extension. But that will be the topic of another post.
Beppu is actually very famous for its onsens, and if the town itself is not particularly attractive, it has on the other hand plenty of high quality onsens, and a local "specialty": sightseeing onsens! Those are called jigoku-onsen (jigoku means "hell") featuring extremely hot water (180-190°F, who would want to bathe anyway?)...Here is a guided tour of the nine main hells...
坊主地獄 : bouzu-jigoku (bonze)
The name comes from the boiling mud forming bubbles that look like bonze heads:
Yes, I know it requires some imagination...
海地獄 : umi-jigoku (sea)
With its milky blue color and amazing 200m depth, it was created 1200 years ago by a volcanic eruption:
Tired? How about a little break?
鬼石坊主地獄 : oniishibozu-jigoku (demon stones and bonze)
Here are the demon stones:
And you already saw the bonzes in the first hell.
山地獄 : yama-jigoku (mountain)
I don't really know where the name comes from (maybe because the source is located at the foot of a small cliff), but the heat and vapor are impressive:
かまど地獄 : kamado-jigoku (oven)
This site, which was used for cooking (!), has several small ponds, here is the one I preferred:
If you have a cold, you can inhale vapor to alleviate it:
鬼山地獄 : oniyama-jigoku (demon mountain)
These crocodiles are perfectly adapted to the peculiar climate of that onsen.
白池地獄 : shiraike-jigoku (white pond)
The color says it all:
血の池地獄 : chinoike-jigoku (blood pond)
Once again, the color explains the name:
竜巻地獄 : tatsumaki-jigoku (tornado)
A geyser that erupts every 25 minutes:
There's a tenth hell, but it's really too tacky...