Tsukahara, Yufu, Oita
Tsukahara Onsen Kakou-no-Izumi
A strongly acidic spring near the volcanic crater, with indoor, outdoor and family-bath options. The operator describes all of them as untreated, source-flowing baths; even soap and shampoo cannot be used because of the water's acidity.
Check before bathing
- Opening hours
- April–November 09:00–18:00 (outdoor bath until 17:30); December–March 10:00–17:30. Last admission 17:00 in both periods. Closed over the New Year period and during severe weather. Indoor bath ¥500; public outdoor bath ¥600; family bath ¥2,000 per room for 60 minutes, including up to two adults and two children aged 1 or older.
Spring & water temperature
- Spring-source temperature
- No fixed value published in the current main official text pages.
- Bathing temperature
- Not published.
- Spring source
- The current main official text page does not publish a single source name.
- Spring classification
- Acidic, iron-bearing aluminum sulfate spring.
- pH
- About 1.5.
- Flow rate
- Not published.
- Water handling
- The operator says the spring is self-flowing and source-flowing: no circulation, filtration, heating or water addition. This applies to the indoor, public outdoor and family-bath products; the current text does not identify the four family rooms as private outdoor baths.
Because the water is strongly acidic, the operator says soap and shampoo cannot be used in the spring. Spring temperature is not substituted for a bath temperature.
How to read a bath profile
Spring-source temperature and actual bathing temperature are kept separate. Each score is shown independently for comparison rather than collapsed into one overall score.
