Seiyo Onsen

Seiyo, a sprawling municipality in the mountains of western Ehime on the island of Shikoku, is traversed by the Shigenobu River and ringed by forested ridges that isolate it from the island's coastal bustle. The onsen here draws sodium-chloride water at 41 °C — a saline warmth with a neutral pH of 7.3 — that wraps bathers in the kind of deep, lasting heat traditionally associated with mountain hot springs in Shikoku. Visitors following the island's famous 88-temple pilgrimage circuit have long made use of Seiyo's thermal waters as a way to rest weary limbs amid the cool, resinous air of the inland forests.