Kaitorima Onsen
- Location
- Matsumae, Hokkaido, Japan
- Water type
- sodium chloride
- Temperature
- 41 °C
- pH
- 7.3
Water profile
Relaxing — deep, immediate muscle release.
Loaded with major ions — the essential minerals (Ca, Mg).
Dense, salty water — you float without effort.
Kaitorima Onsen is an iodine-rich thermal spring in Japan, its mineral-bearing waters carrying the coastal sedimentary mineral character that concentrates iodine compounds from ancient marine geological formations in the groundwater feeding this distinctive spring type along Japan's geologically layered coastal zones. Iodine springs are traditionally associated with well-being in Japanese thermal culture, and the characteristic warmth of iodine-rich waters—which retain heat in the body longer than simple springs through the yudamari (post-bath warmth retention) effect—makes them particularly sought in colder seasons when sustained warmth is most appreciated. This spring's iodine mineral profile places it within a distinguished tradition of Japanese coastal and lowland springs valued since the earliest recorded history of thermal bathing on the archipelago.