Radium Onsen
Osaka, Osaka, Japan
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- Location
- Osaka, Osaka, Japan
- Water type
- radioactive
- Temperature
- 41 °C
- pH
- 7.3
Water profile
Thermicity
Sedative
LowHigh
Relaxing — deep, immediate muscle release.
Mineralisation
Bio-active
LowHigh
Rich in active gases or metals — a strong mineral character.
Buoyancy
Standard buoyancy
LowHigh
Soft water — natural, classic buoyancy.
RadonLithiumBicarbonates
Radium Onsen, in Osaka, takes its name from its naturally radioactive spring at 41°C. The bathhouse offers an indoor bath, an outdoor rotenburo and a sauna.
Insider tip — Radium Onsen in southern Osaka draws on a mildly radioactive radon-bearing spring, a type known in Japan as hoshiyu and historically valued for stimulating circulation and relieving nerve pain. The water emerges at 41°C with a faint mineral tang and a silky, almost slippery feel against the skin. The compact bathhouse preserves a classic sento layout, with deep soaking tubs and a cool plunge pool arranged for alternating hot-cold contrast. Regulars visit several times per week, treating the experience more as maintenance than indulgence.
Nearby
Frequently asked questions
How hot is the water?
The water runs quite hot here, around 41 °C — a sedative water that brings immediate muscle release.
What type of water is found here?
This spot features radioactive water.
What is the best season to visit?
The most favourable period for this spot is: Toute l'année (idéal automne-hiver).