Japanese Onsen & Sauna Guide
Spring Quality & Science
Deep dive into onsen spring types, components, and scientific knowledge
Japanese Onsen & Sauna Guide
Spring Quality & Science
Deep dive into onsen spring types, components, and scientific knowledge
AllBasic Knowledge and IntroductionThe Appeal of Japan's Hot Springs and SaunasHealth & BenefitsSpring Quality & ScienceThematic GuidesTips for a Successful Trip
26 articles in total
Spring Quality & ScienceHot Spring Colors & Scents
Why Hot Springs Look Blue: The Color Explained
Why do some hot springs look cobalt blue, pale blue, or emerald? Learn how Rayleigh scattering, silica and sulfur colloids, Beppu's Umi Jigoku, and bathing cautions shape the color.
Dec 24, 2025
Spring Quality & ScienceHot Spring Colors & Scents
