Photo: Highten31 · CC BY-SA 3.0 · Wikimedia Commons
Rausu Onsen is a hot spring town in Hokkaido, Japan. The water leaves the ground at 99°C, hot enough that it has to be cooled before anyone can get in. Officially the water is classed as chloride spring and sulfur spring. 6 inns take visitors here.
Salty water. The salt leaves a thin film on the skin, so you stay warm well after leaving the bath.
The classic rotten-egg smell and milky white water. It can tarnish silver jewellery, so take it off.
Figures from the town's Japanese Wikipedia article.
44.0317, 145.1553 — open the map
Planning a first soak? Read how an onsen stay works, and what to do if you have tattoos.