The tallest Unzen jigoku also has the most intimidating name: Daikyokan Jigoku, or the Great Howling Hell.
Recall that Unzen was once a center of Buddhist spirituality, which influenced the names of locations in the region. This is another example. The story goes that the Great Howling Hell is one of 16 realms sinners are sent to, where liars are tortured by demons. It does not take much imagination to understand why Daikyokan Jidoku earned its name: the sound of hot gas escaping from volcanic vents can sound like wailing from the underworld, especially at night.
　Daikyokan Jidoku is the most active of Unzen’s jigoku. The water here is particularly hot and acidic, but this was not always the case. The liveliest spot of activity has been slowly moving from west to east. The Kyūhachiman Jigoku has stopped emitting gas altogether, and the Gensei Marsh, a former jigoku, has turned into a beautiful marshland. It is likely that over time the Great Howling Hell will become more peaceful as well.