Salty water. The salt leaves a thin film on the skin, so you stay warm well after leaving the bath.
Clear water with a faintly bitter taste. Known for holding heat.
Turns reddish brown as the iron meets air. The water is clear at the source.
The classic rotten-egg smell and milky white water. It can tarnish silver jewellery, so take it off.
Planning a first soak? Read how an onsen stay works, and what to do if you have tattoos.