ONSEN COLUMN

Onsen Guides & Columns

Curated articles on hot spring types, minerals, indications, and safe bathing. Sourced from Japan’s Ministry of the Environment guidelines.

READ IN 5 LANGUAGES

Read in 5 languages

FEATURED ARTICLES

ETIQUETTEMay 6, 2026· 2min read

Japanese Onsen Etiquette Guide | Washing, Towels & Bathing Rules

Japan's hot spring culture places high value on cleanliness and consideration for others. Here's everything first-time onsen visitors need to know — from the changing room to the bath.

ETIQUETTEMay 6, 2026· 1min read

Onsen-Hopping Order | How to Visit Multiple Hot Springs in One Day

When visiting multiple hot springs in a single day (hashigo-yu), the order you bathe in matters. Japan's Ministry of the Environment recommends moving from low-osmotic to high-osmotic springs to minimise strain on the body.

ETIQUETTEMay 6, 2026· 2min read

Tattoos at Japanese Onsen | Policies, Alternatives & Tips for Visitors

Many Japanese hot spring facilities restrict entry for guests with tattoos. Here's why the policy exists, how it's changing, and the practical options available to tattooed visitors.

SPRING TYPES

Spring Types

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SPRING TYPEMay 5, 2026· 2min read

Chloride Springs: Benefits, Indications & Recommended Onsen

Chloride springs (Cl⁻ as the main anion) are known as "the hot-retaining waters" because the salt coating on your skin keeps body heat from escaping after bathing. Excellent for cold sensitivity and dry skin.

SPRING TYPEMay 5, 2026· 1min read

Simple Springs (Tanjun Onsen): Gentle Waters for Everyone

Simple springs have dissolved components below 1,000 mg/kg and a source temperature of 25°C or above. Mild and non-irritating, they are safe for all ages. Alkaline simple springs (pH 8.5+) are famous for leaving skin silky smooth.

SPRING TYPEMay 5, 2026· 2min read

Bicarbonate Springs: "Beauty Waters" for Smooth, Glowing Skin

Bicarbonate springs (HCO₃⁻ as the main anion) are known as "the beauty waters" because bicarbonate gently removes dead skin cells and sebum, leaving skin silky smooth. Indicated for bathing (cuts, cold sensitivity, dry skin) and drinking (gastroduodenal ulcers, diabetes, gout).

SPRING TYPEMay 5, 2026· 1min read

Sulphate Springs: "The Healing Waters" for Wounds, Skin & Digestion

Sulphate springs (SO₄²⁻ as the main anion) are called "the healing waters" for their anti-inflammatory, skin-moisturizing properties. Indicated for bathing (cuts, cold sensitivity, dry skin, depression) and drinking (biliary dysfunction, dyslipidemia, constipation).

SPRING TYPEMay 5, 2026· 1min read

Carbon Dioxide Springs: "The Bubble Waters" for Gentle Circulation

Carbon dioxide springs contain CO₂ at 1,000 mg/kg or more — bubbles adhere to skin on bathing, earning the nickname "the bubble waters." CO₂ absorbed through skin dilates capillaries, warming the body even in lukewarm water (35–38°C) with minimal cardiac strain.

SPRING TYPEMay 5, 2026· 1min read

Ferruginous Springs: Iron-Rich Waters for Anemia & Unique Rust-Red Baths

Ferruginous springs contain iron ions (Fe²⁺ + Fe³⁺) at 20 mg/kg or more. Clear at the source, they turn reddish-brown or golden on contact with air. Indicated for drinking to help with iron-deficiency anemia.

MINERALS

Mineral Guide

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MINERALMay 5, 2026· 2min read

Metasilicic Acid: The "Beauty Spring" Standard Mineral & Top 5 Onsen

Metasilicic acid (H₂SiO₃) is a natural moisturizer also found in skincare lotions. Hot springs containing more than 50mg/kg are called "beauty springs" — leaving skin hydrated long after bathing. This is one of the therapeutic spring criteria in Japan's Mineral Spring Analysis Guideline (Table 1-1).

MINERALMay 5, 2026· 1min read

Sodium ion: Main Effects & Top 5

Sodium ion (Na⁺) is the key component of chloride and bicarbonate springs. It forms a thin salt film on the skin, locking in warmth long after bathing.

MINERALMay 5, 2026· 1min read

Calcium ion: Main Effects & Top 5

Calcium ion (Ca²⁺) exerts an astringent action that tightens the skin. Its calming properties help soothe flushing and inflammation after bathing.

MINERALMay 5, 2026· 1min read

Magnesium ion: Main Effects & Top 5

Magnesium ion (Mg²⁺) is easily absorbed transdermally during bathing, helping relax muscle stiffness and supporting skin hydration.

MINERALMay 5, 2026· 1min read

Iron ion: Main Effects & Top 5

Iron(II) ion (Fe²⁺) is the marker of iron-rich springs. The water turns yellow-brown to red-brown when exposed to air, offering strong heat retention.

MINERALMay 5, 2026· 1min read

Sulfide ion: Main Effects & Top 5

Sulfide ions (S²⁻, HS⁻) are the key components of sulfur springs. Their strong antibacterial action removes bacteria and irritants from the skin surface.

SAFETY

Bathing Safety

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SAFETYMay 6, 2026· 1min read

Before You Bathe: Preparation & Safety Checklist | Ministry of Environment Guidelines

Safe and comfortable hot spring bathing starts before you step in. Based on Japan's Ministry of the Environment pamphlet, here's what to do — and what to avoid — before entering an onsen.

SAFETYMay 6, 2026· 1min read

Safety During Hot Spring Bathing | Heat Stroke, Heat Shock & Soaking Time

Most hot spring accidents happen during bathing itself. Heat shock (sudden blood pressure changes from temperature swings), overheating, and dehydration from prolonged soaking are all preventable — here's how.

SAFETYMay 6, 2026· 1min read

Drinking Hot Spring Water (Insatsu) | What It Is, Benefits & Safety Rules

Insatsu — drinking hot spring water directly — has a long history in Japan and Europe. Certain spring types are recognised to support digestive and metabolic health, but the practice is strictly regulated and must be done at authorised facilities only.

SAFETYMay 6, 2026· 1min read

Hot Spring Contraindications | Conditions & Situations to Avoid Bathing

Certain medical conditions and physical states are considered contraindications for hot spring bathing — meaning bathing could pose a risk to your health. Based on the Ministry of the Environment guidelines, here is what to know before you soak.

SYMPTOMS

Symptom Guide

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SYMPTOMSMay 6, 2026· 1min read

Hot Springs for Cold Sensitivity | 4 Spring Types Explained

Discover which hot spring types are officially indicated for cold sensitivity and peripheral circulatory disorders, based on Japan's Ministry of the Environment guidelines. Chloride springs form a heat-retaining salt film on the skin, while carbon dioxide springs dilate blood vessels directly through the skin without stressing the heart.

SYMPTOMSMay 6, 2026· 1min read

Peripheral Circulation Disorders & Onsen | All 10 Spring Types Indicated

Peripheral circulation disorders — poor blood flow to the extremities — carry a general bathing indication across all 10 Japanese spring types recognised by the Ministry of the Environment. Thermal dilation of peripheral blood vessels is the core mechanism, with sulfur springs (hydrogen sulfide type) additionally holding a specific type indication.

SYMPTOMSMay 6, 2026· 1min read

Hot Springs for Fatigue Recovery | All 10 Spring Types

Fatigue recovery and health promotion are general bathing indications recognised across all 10 Japanese hot spring types, from simple springs to radioactive springs. Three physical mechanisms — thermal, hydrostatic, and buoyancy — work together to flush metabolic waste, reduce swelling, and deeply relax muscles regardless of mineral content.

SYMPTOMSMay 6, 2026· 1min read

Hot Springs for Autonomic Disorder & Stress | Ministry-Approved Guide

Autonomic nervous system disorder is a general bathing indication recognised across all 10 Japanese spring types. Simple springs additionally carry a specific indication for stress relief and autonomic instability. The thermal, buoyancy, and hydrostatic mechanisms of onsen bathing shift the nervous system toward parasympathetic dominance, helping to reset mind and body.

SYMPTOMSMay 6, 2026· 1min read

Hot Springs for Insomnia | General Indication Across All 10 Spring Types

Insomnia is listed as a general bathing indication for all 10 Japanese spring types. Simple springs carry an additional specific indication for insomnia, making them the gentlest choice for sensitive bathers. The key mechanism is the "core temperature rhythm": bathing temporarily raises deep body temperature, and the subsequent drop 1–2 hours later triggers natural sleep onset.

SYMPTOMSMay 6, 2026· 1min read

Hot Springs for Chronic Joint Pain & Neuralgia | All 10 Spring Types Including Radon

Chronic muscle pain, joint pain, and neuralgia are general bathing indications for all 10 Japanese spring types. Radioactive springs (radon springs) additionally carry specific indications for gout and rheumatoid arthritis. The combined effects of heat, hydrostatic pressure, and buoyancy — reinforced by mineral-specific actions — offer meaningful symptom relief.

FAQ

Onsen FAQ

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FAQMay 6, 2026· 1min read

What Is an Onsen? | Japan's Hot Spring Definition & 3 Legal Conditions Explained

In Japan, the term 'onsen' is strictly defined by the Hot Spring Act. A natural spring must meet at least one of three conditions — temperature, dissolved solids, or specific minerals — to qualify.

FAQMay 6, 2026· 1min read

What Is Spring Type (Senshu)? | Japan's 10 Hot Spring Classifications Explained

Spring type (泉質, senshu) classifies hot springs by their dominant dissolved minerals. Japan's Ministry of the Environment recognises 10 types, each with specific health indications and contraindications.

FAQMay 6, 2026· 1min read

What Is a Hot Spring Analysis Certificate? | Legal Requirements & How to Read It

Every licensed onsen facility in Japan is required by law to display an official hot spring analysis certificate (温泉分析書). It documents the spring's chemistry, pH, spring type, and health indications — here's what to look for.

FAQMay 6, 2026· 1min read

What Are General Indications? | Health Benefits Common to All Hot Spring Types

General indications are health benefits officially recognised for all hot spring types, regardless of spring chemistry. They arise from the physical effects of hot water — heat, buoyancy, and hydrostatic pressure.

FAQMay 6, 2026· 1min read

What Are Contraindications for Onsen? | Conditions & Diseases That Prohibit Bathing

Contraindications are medical conditions or states where hot spring bathing may worsen symptoms or cause serious harm. Japanese onsen facilities are legally required to post contraindication lists.

FAQMay 6, 2026· 1min read

What Is Insatsu (Drinking Onsen Water)? | Culture, Benefits & Safety

Insatsu (飲泉) — drinking natural mineral spring water — is an ancient form of spa therapy popular in Europe and practised in select Japanese onsen facilities licensed by prefectural governments.

ETIQUETTE

Onsen Etiquette

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ETIQUETTEMay 6, 2026· 2min read

Japanese Onsen Etiquette Guide | Washing, Towels & Bathing Rules

Japan's hot spring culture places high value on cleanliness and consideration for others. Here's everything first-time onsen visitors need to know — from the changing room to the bath.

ETIQUETTEMay 6, 2026· 1min read

Onsen-Hopping Order | How to Visit Multiple Hot Springs in One Day

ETIQUETTEMay 6, 2026· 2min read

Tattoos at Japanese Onsen | Policies, Alternatives & Tips for Visitors

Many Japanese hot spring facilities restrict entry for guests with tattoos. Here's why the policy exists, how it's changing, and the practical options available to tattooed visitors.

ETIQUETTEMay 6, 2026· 1min read

Mixed-Gender Bathing (Konyoku) in Japan | History, Rules & What to Expect

Japan has two hot spring bathing styles: konyoku (mixed-gender) and gender-separated baths. Mixed bathing is an ancient Japanese tradition, but it has become increasingly rare — most modern facilities use separate male and female sections.

ETIQUETTEMay 6, 2026· 1min read

Private Family Baths (Kashikiri-buro) | How to Book & What to Expect

A kashikiri-buro (貸切風呂) is a private hot spring bath reserved exclusively for one group during a set time slot. Ideal for families with children, couples, and guests with tattoos, these private baths offer all the benefits of a natural hot spring in a personal, stress-free setting.

ETIQUETTEMay 6, 2026· 1min read

Onsen with Kids | Age Rules, Safety Tips & Choosing the Right Facility

Taking children to a Japanese hot spring can be a wonderful experience — but there are important age limits, safety precautions, and etiquette considerations to be aware of. Here is everything parents need to know.

ONSEN AREAS

Onsen Areas

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famous-onsenMay 9, 2026· 3min read

Bessho Onsen: A historic 'Beauty Bath' in the 'Kamakura of Shinshu'

Known as the "Kamakura of Shinshu," Bessho Onsen in Ueda, Nagano, is a historic hot spring with over 1,400 years of history, even mentioned in "The Pillow Book." Famed as a "Bijin-no-yu" (Beauty Bath) for its skin-smoothing waters, it's a charming town centered around Kitamuki Kannon Temple and other historic sites.

famous-onsenMay 9, 2026· 3min read

Nagato Yumoto Onsen: A Stylish, Reborn Riverside Hot Spring Town

This is Yamaguchi Prefecture's oldest onsen, with a history of about 600 years. A recent redevelopment, including by Hoshino Resorts, has transformed it into a chic town with terraces and cafes along the Otozure River, perfect for a stroll.

famous-onsenMay 9, 2026· 3min read

Ito Onsen: A Historic Hot Spring Town with Abundant Waters

Located on the east coast of the Izu Peninsula in Shizuoka, Ito Onsen boasts one of Japan's most plentiful supplies of hot spring water, enjoyed in numerous inns and homes.

famous-onsenMay 9, 2026· 3min read

Hachimantai Onsen-go: A Hot Spring Village with Diverse Waters in a National Park

Nestled in the grand nature of Towada-Hachimantai National Park, Hachimantai Onsen-go is a collection of hot spring resorts scattered throughout primeval beech forests. Each boasts its own unique water quality. From milky white sulfur springs to rare mud baths, it's a place where you can heal both mind and body while enjoying a tour of unique hot springs.

famous-onsenMay 9, 2026· 3min read

Myoken Onsen: A Historic Hot Spring Retreat Along the Amorigawa River

Nestled in a valley along the Amorigawa River and close to Kagoshima Airport, Myoken Onsen is a historic spa town once visited by Ryoma Sakamoto. It is renowned for its abundant, free-flowing spring water and diverse mineral qualities.

famous-onsenMay 9, 2026· 3min read

Kirishima Onsen-go | A diverse hot spring village steeped in mythology

Kirishima Onsen-go is a collection of hot springs at the foot of the Kirishima Mountains. Known as the honeymoon spot of historical figure Ryoma Sakamoto, it's a place rich in myth and history, boasting diverse spring qualities and magnificent nature.