Japan Onsen Atlas温泉アトラス
A large milky-white outdoor pool ringed by rocks
Photo information
Yas Nakano CC BY-SA 3.0 View original page

Tohoku · Onsen area

Sukawa Onsen

すかわおんせん · 須川温泉

Iwate · 一関市

OpenNational Health Resort Onsen100 Onsen to Know Japan — No. 16
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Official classification

Spring type (therapeutic classes)

Iron springSulfur springSulfate springChloride springAcidic spring

Official spring-type name (as recorded)Iron(II)- and sulfur-bearing sodium sulfate/chloride spring (hydrogen-sulfide type); old name: acidic iron-salt-glauber-salt hydrogen-sulfide spring. Source name: Sukawa Onsen

Source temperature
49.9°C
pH
2.3
Flow rate
6,000 L/min
Radon
Unconfirmed

Appearance & feel

Water colour · Feel

Milky white

Colour and feel are listed only where a source states them. They vary by day and by bath.

What makes it special

At 1,126 metres on the flank of Mt Kurikoma, 6,000 litres a minute of strongly acidic water pour into Dainichi-yu, an open-air bath big enough for fifty.
Why?

The inn's site gives the altitude as 1,126 m, the flow as 6,000 litres a minute (about thirty oil drums), the pH as 2.2, and the big outdoor bath as holding 30–50 people.[1]

Facilities in this area

Facilities come from the register (Wikipedia, OpenStreetMap, official sites). Those marked "natural spring unconfirmed" are listed on the basis of their name only.

Ryokan (inn) · Seasonal

Sukawa Kogen Onsen (Iwate side)

Day-use bathing
Yes
Fee
¥900checked 2026-10-09
Hours
日帰り入浴 9:00–16:00/宿泊者: 大日湯 6:00–21:00(最終20:30)、大浴場 24時間(清掃8:00–9:00除く)checked 2026-10-09
Official site
Baths4
TypeGenderSourceBath temperatureFree-flowingAdded waterHeatedRecirculatedDisinfected
Open-air bathSeparateSukawa OnsenUnconfirmedUnconfirmed[1]Unconfirmed[1]Unconfirmed[1]Unconfirmed[1]Unconfirmed[1]
Indoor bathSeparateSukawa OnsenUnconfirmedUnconfirmed[1]Unconfirmed[1]Unconfirmed[1]Unconfirmed[1]Unconfirmed[1]
Indoor bathSeparateSukawa Onsen45°CUnconfirmed[1]Unconfirmed[1]Unconfirmed[1]Unconfirmed[1]Unconfirmed[1]
Indoor bathUnconfirmedSukawa Onsen (steam)UnconfirmedUnconfirmed[1]Unconfirmed[1]Unconfirmed[1]Unconfirmed[1]Unconfirmed[1]
Hotel · Seasonal

Kurikoma Sanso (Akita side, Higashinaruse village)

Day-use bathing
Yes
Fee
Unconfirmedno check date
Hours
Unconfirmedchecked 2026-10-09
Official site
Baths1
TypeGenderSourceBath temperatureFree-flowingAdded waterHeatedRecirculatedDisinfected
Open-air bathSeparateSukawa Onsen, pipedUnconfirmedUnconfirmed[3]Unconfirmed[3]Unconfirmed[3]Unconfirmed[3]Unconfirmed[3]

Getting there

Reachable by public transport

From Ichinoseki Station on the Tohoku Shinkansen, the Iwate Kenko bus for Sukawa Onsen takes about 90 minutes and stops right outside the inn (check running dates with the bus company, +81 191-23-4250; no winter service). From the Akita side, take a bus from Yuzawa Station to Oyasukyo Onsen and change to the seasonal, reservation-only Komachi Shuttle taxi. By car: 42 km, about an hour, from Ichinoseki IC on Route 342, or 48 km from Jumonji IC.

Getting there
Ichinoseki Station (Tohoku Shinkansen) · 90
Through the year
Route 342 closes from early November to late April and the inn closes with it. Prefectural Road 282 from Miyagi stays shut until early June. Landslides cause closures at other times too, so check the inn's site and road information first
Checked
2026-10-09
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About the water

Strongly acidic at pH 2.2, with iron, sulfur, sulfate and salt. The source emerges at 48–52°C, about 6,000 litres a minute, and literally flows as a river behind the inn. The inn uses the old term ryokuban-sen (vitriol spring) and notes that four departments of Tohoku University's medical school ran spa-therapy studies here for fifty years; none of this guarantees a benefit. The posted indications specific to this water type are atopic dermatitis, psoriasis, impaired glucose tolerance and skin infections; because of the acidity, people with sensitive skin or mucous membranes are advised against bathing.

Indications (as posted on the analysis)

Posted water-type indications: atopic dermatitis, psoriasis vulgaris, impaired glucose tolerance (diabetes), skin infections. General indications: chronic muscle and joint pain, poor circulation, weak digestion, mild hypertension and others. Water-type contraindications: sensitive skin or mucous membranes, dry skin in the elderly

Indications are an official statement based on the water analysis, not a guarantee of treatment. They are kept separate from opinions.

SourceSource temperaturepHRadonChecked
Sukawa Onsen source502.2Unconfirmedno check date

Three things not to miss

A large milky-white outdoor pool ringed by rocks
Photo information
Yas Nakano CC BY-SA 3.0 View original page
01

Dainichi-yu, the great outdoor bath

Steps from the reception building A pool for 30–50 bathers filled with undiluted source water, divided by a wooden fence into men's and women's sides; the women's side faces the strange Dainichi-iwa rock. Lit at night; open 6:00–21:00, last entry 20:30.

One of the largest outdoor baths in Tohoku, with milky water. Day visitors can use it 9:00–16:00.[1][2]

02

Oiran-buro, the natural steam bath

A hut about 100 m up the slope behind the inn You lay a mat in a one-person bay, lie down without covering the steam vent and pull a blanket over yourself, and the spring's steam envelops you. Daylight hours only, roughly 6:00–16:00; buy the mat at the shop.

A bath of pure steam, named, the story goes, for courtesans who disliked the smell of sulfur on their skin.[1][3]

Hot water running over rocks beside a small wooden building
Photo information
Yas Nakano CC BY-SA 3.0 View original page
03

Trailhead for Mt Kurikoma, and a river of hot water

Around the inn The inn sits at the trailhead for Mt Kurikoma, with a nature path through the Sai-no-kawara boulder field and Nagoriga-hara marsh. Surplus spring water runs off over the rocks into the Yujiri stream and on to the Iwai River, and Mt Chokai stands straight ahead on the horizon.

Hot water, alpine flowers, autumn colour and a mountain climb in one place; the climbing season opens on the third Sunday of May.[3][4][1]

The story

The vinegar river

A document of 873 names the place Sukawa, "vinegar river", for the sour water running down it. By the mid-Edo period people came for cures, and a sulfur mine operated here into the Meiji era. The source lies on the Iwate side; the water once drained toward Akita until, early in the Edo period, the Akita domain refused to pipe it and it was turned down the Yujiri stream into Iwate. In 1958 it was designated a national recuperation spa together with Mayu Onsen.[3]

Two prefectures, two inns

An inn stands on each side of the prefectural line. Sukawa Kogen Onsen on the Iwate side, once run by village notables, became a company in 1957 and a designated people's lodge in 1959; by the late 1980s it had many buildings, a thermal pool and a consultation room staffed by Tohoku University doctors. The present building dates from 1998 and all 36 rooms were refitted in 2021. Kurikoma Sanso on the Akita side is owned by Higashinaruse village, pipes its water from Sukawa and has a panoramic outdoor bath facing Mt Chokai.[3]

A spa with a season

Route 342 is buried from early November to late April and the inn closes with it. After the 2008 Iwate-Miyagi earthquake the road from Iwate stayed shut for almost two years, and landslides still bring closures. The inn asks visitors to check road conditions before setting out. A mountain spa like this comes with its own calendar.[3][2]

Going solo

Solo stay unconfirmedYes
Weekend / peak restrictionsUnconfirmed
Where to eat dinnerThe inn's meals or its canteen (serving curry and the like since the 2021 refurbishment). Nothing else nearby
Private bathUnconfirmed

checked 2026-10-09

Through the year

Recommended months

JanFebMarAprMayJunJulAugSepOctNovDec

Months open

JanFebMarAprMayJunJulAugSepOctNovDec

"Recommended" and "open" are recorded separately. Check the season for seasonal springs.

May — Opens just before the Golden Week holidays; the mountain officially opens on the third Sunday of May, and trails may still be under snow

Jun · Jul — Alpine flowers and the song of the Ezo cicada

Sep · Oct — Autumn colour on Mt Kurikoma; the inn shuts for winter in early November

Nov · Dec · Jan · Feb · Mar · Apr — Route 342 is closed and so is the inn

Food, culture & experiences

Available / bookable

Climbing Mt Kurikoma by the Sukawa route

The Sukawa route via Lake Showa takes 3.5–4 hours round trip (Kurikoma Sanso's guidance); in 2026 the whole route reopened on 18 July[4]

The inn is the trailhead
Available / bookable

Sai-no-kawara and Nagoriga-hara

A boulder field and a marsh along the nature path[3]

On foot from the inn (time not confirmed)
Available / bookable

Refresh Road R342

The inn's nickname for Route 342 up the mountain, with seasonal viewpoints[2]

The road to the inn

Editors' guide

Day bathing runs 9:00–16:00. A ticket covers either Dainichi-yu or an indoor bath, so for both, buy the 1,400-yen combined ticket after 14:00. For the steam bath, buy a mat at the shop and go while it is light. Overnight guests get the silhouette of Mt Chokai from Dainichi-yu at dusk. Buses back are few; fix your return time first.

The "editors' guide" above is written by the editors from sources; it is not a visitor's opinion.

Photo gallery

Visitor reviews

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Review posting is in preparation, with visit date, facility, comments on water, scenery and access, photos, language and reporting.

Onsen areas nearby

Unconfirmed & notes

  • The 873 record, the mine, the 1958 designation, the 1998 building, the 2021 refurbishment and the 90-minute bus time are from Wikipedia (CC BY-SA)
  • Free-flow/dilution notices, tattoo policy, and Kurikoma Sanso's day-use fee and hours are unconfirmed
  • Exact 2026 opening and closing dates and the bus service period were not confirmed

Sources

  1. 温泉 | 須川高原温泉【公式サイト】須川高原温泉 · 2026-10-09
  2. 料金・予約・アクセス | 須川高原温泉【公式サイト】須川高原温泉 · 2026-10-09
  3. 須川温泉 - Wikipedia(日本語版)Wikipedia · 2026-10-09
  4. 栗駒山荘 公式サイト栗駒山荘(東成瀬村) · 2026-10-09

Register sources

Data status

Name & locationPublishedCoordinatesPublishedSpring typePublishedPhotosPublishedFacilitiesPublishedVisiting info (dated)PublishedEditorial articlePublished

Updated 2026-10-09

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