Salty water. The salt leaves a thin film on the skin, so you stay warm well after leaving the bath.
Smooth, slightly slippery water. Often nicknamed bihada-no-yu, the water for beautiful skin.
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.