Turns reddish brown as the iron meets air. The water is clear at the source.
Strongly acidic, sometimes below pH 2. It stings on cuts and is not for long soaks.
The classic rotten-egg smell and milky white water. It can tarnish silver jewellery, so take it off.
37.7608, 140.2224 — open the map
Planning a first soak? Read how an onsen stay works, and what to do if you have tattoos.