吹上温泉 is a hot spring town in Hokkaido, Japan. Officially the water is classed as chloride spring, sulfate spring and acidic spring.
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.
Strongly acidic, sometimes below pH 2. It stings on cuts and is not for long soaks.
43.4315, 142.6416 — open the map
Planning a first soak? Read how an onsen stay works, and what to do if you have tattoos.