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Shima Tamura

四万たむらよんまんたむら

Lodging
Kanto·Gunma

Day Use

No

Bathing & Water

Natural onsen water

Uses natural hot spring water

Outdoor BathYes

Open-air outdoor bath

Indoor BathYes

Enclosed indoor bathing area

SaunaYes

Dry heat sauna room

Capabilities

Private BathYes

Private bath available for day-use visitors or hotel guests to reserve

Room OnsenYes

Private onsen bath in guest rooms, for overnight guests only

Mixed BathingYes

Shared bathing area for all genders

Policies & Services

DiningYes

Restaurant or dining open to visitors (not just hotel meal plans)

WashingYes

Shower, wash stations, soap and shampoo provided

TowelsYes

Towels available to rent or borrow

Rest AreaYes

Relaxation space for after bathing

ParkingYes

On-site or nearby parking available

岩根の湯

Shima Onsen Iwane no Yu

Operated by · 有限会社 田村旅館

Chloride
+ Sulfate
Color
colorless and transparent
Taste
not recorded
Odor
not recorded

Sodium-Calcium Chloride-Sulfate spring

pH 6.3NeutralHot source · 65°CHigh silica
Composition fingerprint1.9 g/kg dissolved · Hypotonic
Na⁺71
Ca²⁺23
Cl⁻74
SO₄²⁻24
CationsAnions
Sodium Na⁺
salt's cation — pairs with chloride to make the water salty.
Chloride Cl⁻
table-salt anion — coats the skin and holds heat in.
Known good for
  • Warmingcold sensitivity
  • Circulationtired legs
  • Aches & jointsstiff shoulders

A sodium-calcium chloride spring rising unaided at Shima, with sulfate adding quiet body to the water. The pH is neutral and the mineralization moderate at 1,880 mg/kg, so the water has noticeable substance without any sharpness. A generous 133 mg/kg of metasilicic acid puts it in Japan's beauty-water family: the silica leaves a thin film that makes skin feel smoother once you are out of the bath.

Sampled at wellhead·Analyzed Feb 6, 2013·一般社団法人 群馬県薬剤師会(環境衛生試験センター)

Explore the water

Views

Forest
Waterfall
River

Highlights

Drinking Spring
Foot Bath

About

A sprawling ryokan with six hot spring baths drawing from sodium-calcium chloride-sulfate water. One of them, the Ryugu (竜宮), is a secluded mixed bath tucked away in the property. The inn has been built up over centuries since 1563, and different wings have very different characters, some with old wooden beams and tatami that feel properly historic. Shima Onsen itself sits in a narrow mountain valley in Gunma.

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5.0

4 reviews

from 1 reviewer

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Sergey M
6 months ago· edited

Double meals, dinner and breakfast, at Shima Tamura, Shima Onsen 13.01.2026 14.01.2026

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Sergey M
6 months ago· edited

797. Shima Tamura, Shima Onsen, Gunma (pt.3) ★★★ About the onsen: 7. Morinokodama. Outdoor bath. View of a waterfall, forest, and river. There are fences, but they are in the lower part, so the view is still great. The water is clear, temperature 40-41. 8. Ouketsu Momiji. Changes by gender. A small bath in the rock with an awning made of white fabric. The first part of the bath is shallow, the second is deeper. There is not much of a view, but this bath does not need one. It creates a natural atmosphere, like sitting somewhere between the rocks in hot water. The water is clear, temperature 41. 13.01.2026 14.01.2026

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Sergey M
6 months ago· edited

797. Shima Tamura, Shima Onsen, Gunma (pt.2) ★★★ About the onsen: 4. Ryugu. Outdoor mixed baths in stone. Clothing is allowed, but not required. View of the forest, small waterfalls, and a nearly dry river. 4.1. Outdoor stone bath closer to the small waterfalls. The water is clear, with a slight greenish tint. Temperature 40. 4.2. Outdoor stone bath. The water is clear, temperature 44. 5. Irakanoyu. Large indoor bath area. It is comfortable to breathe inside. 5.1. Three adjoining baths with clear water. Temperatures 44, 44, and 35.5. 5.2. Separate bath, divided into two. The water is clear, temperatures 45 and 42. 6. Gomusounoyu. Changes for men and women. Atmospheric indoor wooden bath. The water is clear, temperature 45. It is comfortable to breathe inside. 13.01.2026 14.01.2026

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Sergey M
6 months ago

797. Shima Tamura, Shima Onsen, Gunma (pt.1) ★★★ Stayed overnight. I took the half-board plan, breakfast and dinner, served in a separate room, and the food itself was all good. No day-use bathing. The staff were Japanese, and some employees spoke English well. I got a free room upgrade, they gave me a room on the upper floors with an onsen in the room. The ryokan has many different baths, and the baths are switched between men and women. There is a private bath for ¥2,200, I did not use it. A top place in terms of onsen variety, several rotenburo with great views, konyoku, several atmospheric small rotenburo, and different good indoor baths. A top place, highly recommended. A serious competitor to Sekizenkan in Shima Onsen. About the onsen: 1. Small wooden bath in the room. Empty by default, hot onsen water is filled from the tap. The water was clear, and after filling the temperature was 47, you can dilute it with cold water. It was comfortable to breathe inside. 2. Ouketsu Tsubaki. Switched between men and women. A small outdoor stone bath. There is not much of a view, only trees above, but it is cozy. The water was clear, at first the temperature at the surface was 47.2, but after mixing the water it became 42.5-43. 3. Iwanenoyu. Breathing inside was fine. 3.1. Indoor bath with clear water, temperature 43. 3.2. Sauna. 13.01.2026 14.01.2026

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Last updated August 4, 2026