The hell of Sulfur Onsen (硫黄地獄, iojigoku) is a wild Onsen located in Hakone. It is also one of the onsen springs for Hakone Onsen. It is strong acid water with sulfur. You can smell of Onsen.

Tourist Info.
Don't touch the spring water because it is very hot! It is not the tourist attraction, so any activity here takes your own responsibility. Never drop any liquid into this spring because it is used public Onsen.

Access
0. at Hakone Station
1. use Hakone Tozan Line to Kowakudani(33 min.)
2. use bus to Ashinoyu
3. walk north (1 hr.)