Japanese Onsen & Sauna Guide
Spring Quality Details
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
11 articles in total
Spring Quality & ScienceSpring Quality Details
Carbonated Hot Springs: Features and Famous Baths
What is a carbonated hot spring? Learn the standard of 1,000 mg/kg or more of free carbon dioxide set by Japan’s Ministry of the Environment. Discover how tiny bubbles form on the skin, why these baths are served lukewarm, famous hot springs like Nagayu, and the difference between natural and artificial carbonated baths.
Dec 24, 2025
Spring Quality & ScienceSpring Quality Details
Radon Hot Spring Standards and Safety
What is a radioactive hot spring? Learn the official standard set by Japan’s Ministry of the Environment: radon 8.25 Mache units = 111Bq/kg. Explore famous baths, the science of hormesis, and key safety tips.
Dec 24, 2025
Spring Quality & ScienceSpring Quality Details
Iodine-Rich Hot Springs: Seawater Geology and Safe Drinking
Discover iodine-rich hot springs common near coasts such as Chiba. Learn about their characteristic odor, why they occur, drinking rules, and thyroid risks.
Dec 24, 2025
Spring Quality & ScienceSpring Quality Details
Why Iron Springs Turn Reddish Brown and Famous Baths
What is an iron spring? Learn the Ministry of the Environment standard of 20 mg/kg or more of total iron ions, why clear water turns reddish brown by oxidation, famous baths like Arima, Nagayu, and Ikaho, and the difference between bathing and drinking it.
Dec 24, 2025
Spring Quality & ScienceSpring Quality Details
Acidic Hot Springs: Standards, Famous Baths, and Skin Care
Learn how acidic hot springs are defined under Japan’s Ministry of the Environment standards, plus famous baths like Kusatsu, Tamagawa, and Zao, and key cautions for skin, eyes, and wounds.
Dec 24, 2025
Spring Quality & ScienceSpring Quality Details
Sulfur Springs Guide: Top Hot Springs and How to Enjoy
What are sulfur hot springs? Learn their place among medicinal springs, top spots like Takayu, Manza, and Tsukioka, regional differences, how to bathe, what to bring, and common indications.
Dec 24, 2025
Spring Quality & ScienceSpring Quality Details
Sulphate Springs: Features and Safe Soaking Tips
Learn what sulfate hot springs are, how calcium- and sodium-types differ, how they feel, why called 'wound baths', and key safety tips for bathing and drinking.
Dec 24, 2025
Spring Quality & ScienceSpring Quality Details
Bicarbonate Springs: Soft Skin Feel and Moisture
Confused by bicarbonate hot springs? Learn why they're called beauty baths, how the water affects skin, and post-bath hydration and safety tips for beginners.
Dec 24, 2025
Spring Quality & ScienceSpring Quality Details
Chloride Springs: Why They Taste Salty and Stay Warm
Why are some Japanese hot springs salty? Discover the warming benefits of Chloride Onsen, why coastal towns have them, and crucial post-bath rinsing tips.
Dec 24, 2025
Spring Quality & ScienceSpring Quality Details
Why Simple Hot Springs Feel So Gentle
Confused by 'simple' hot springs? Learn why they're not just low-mineral baths. Discover features, who benefits, and why beginners prefer gentle hot springs.
Dec 23, 2025