Iwate · Sukawa Onsen, Mt Kurikoma
Sukawa Kōgen Onsen – Dainichi-yu open-air bath
須川高原温泉 大露天風呂「大日湯」
One of Tōhoku's highest hot springs, at 1,126 m on the northern slopes of Mt Kurikoma. Some 6,000 litres a minute flow like a stream; the strongly acidic alum-vitriol water (pH around 2) carries white mineral flakes and tingles on the skin. The famous big open-air Dainichi-yu is an open, rock-backed pool; day use 6:00–21:00 (until 20:00 on Wednesdays), ¥900. The indoor baths and the 'oiran' steam bath run 9:00–16:00. Because of the altitude, the road and the onsen close in winter (early November to early May). About 95 minutes by bus from Ichinoseki Station to the Sukawa Onsen terminus; it is also the Kurikoma trailhead, busiest in autumn colour season (late Sept–early Oct).
- Price (adult)
- ¥900
- Hours
- 6:00–21:00 (Dainichi-yu open-air bath); 9:00–16:00 (indoor bath)
- Closed
- Closed in winter (early Nov–early May); some Wednesday cleaning closures (check)
- Access
- About 95 min by Iwate Kenkō bus (Sukawa Onsen line, seasonal) from JR Ichinoseki Station to the Sukawa Onsen terminus; 70 min by car from Ichinoseki IC
- Water type
- Acidic spring
- Tattoos
- Ask ahead
- Admission
- 'Dainichi-yu' open-air bath: adults ¥900, children ¥450 (aggregator listing; a 2025 visit report quotes ¥800, so subject to change). The indoor 'Sukawa-no-yu' is charged separately. Cash only, ticket machine. Valuables locker ¥100. Shampoo and body soap provided. Free for guests of Kurikoma Sanso
- Baths
- A large cure-inn at 1,126 m on the flank of Mt Kurikoma where Iwate, Miyagi and Akita meet. Day bathing centres on the detached 'Dainichi-yu' rotenburo (room for 30–50, a wooden fence dividing men and women, the great 'Dainichi-iwa' rock facing the women's side, lit up at night). The indoor 'Sukawa-no-yu' (indoor pool plus small rotenburo) admits day visitors 9:00–16:00. 100 m up behind the inn is the natural-steam 'Oiran-buro', a one-person steam hut used in daylight. Washing facilities are basic — wash hair indoors
- Spring water
- Strongly acidic sulphur spring at pH 2.2 (acidic sulphur-aluminium-sulphate-chloride type), 48–52°C, gushing naturally at 6,000 litres a minute — among Japan's largest flows for a high-mountain spring. From the source field behind the inn it forms a 'river of hot water' that is channelled by wooden flumes into the tubs, free-flowing. Milky to bluish-white and strongly sulphurous; the acidity can sting the skin and hurts the eyes. A 'medicinal spring' studied for 50 years by Tohoku University's medical faculty. Indicated for atopic dermatitis, psoriasis, diabetes, suppurative skin conditions, rheumatism and poor circulation; contraindicated for sensitive skin and dry skin in the elderly
- Access & parking
- Free parking for about 300 cars. By car: about 1 h 10 min (55 km) from Ichinoseki IC on the Tohoku Expressway via Route 342 and Genbikei gorge. By bus: about 1 h 30 min on the seasonal Iwate Kenkotsu 'Sukawa Onsen' service from JR Ichinoseki Station (2–3 a day, terminus). The Kurikoma section of Route 342 is closed from early November to early May. Trailhead for Mt Kurikoma (about 2 hours to the summit)
- Phone
- 0191-23-9337
- Official site
- sukawaonsen.jp ↗
- Open in Google Maps
- Google Maps ↗
Essentials
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Why go
- 1,126 m up; 6,000 L/min of strongly acidic water
- Big rock-backed open-air bath, ¥900
- Closed Nov to early May
At 1,126 m, a pH 2.2 'medicinal spring' flowing 6,000 litres a minute
Sukawa Kogen Onsen is a large cure-inn at 1,126 m on the flank of Mt Kurikoma, where Iwate, Miyagi and Akita meet, in Ichinoseki, Iwate; its showpiece for day visitors is the great open-air bath 'Dainichi-yu'. Known as a healing resort for more than 1,100 years since the early Heian period and studied for half a century by Tohoku University's medical faculty as a 'medicinal spring', its strongly acidic sulphur water (pH 2.2) gushes naturally at 48–52°C and a staggering 6,000 litres a minute. The river of hot water flowing from the source field behind the inn is led by wooden flumes into a vast rock pool for 30–50 bathers, free-flowing, with the great 'Dainichi-iwa' rock looming over the women's side. Open from 6 a.m. to 9 p.m., it rewards hikers before or after Mt Kurikoma, and at dawn in the mist or at night under floodlights you soak above the clouds.
Milky water with an acidic tingle — and the 'Oiran-buro' steam hut
At Dainichi-yu you take off your shoes; the women's bath is at the back, the men's at the front, with no swapping. Each side is a single broad open-air pool edged with natural rock, into which the cloudy water — milky white, bluish on some days — pours down a flume. At pH 2.2 it stings any cut and can quickly redden sensitive skin, so soak in short spells and keep it out of your eyes. Many find the sulphur smell stronger than at neighbouring Kurikoma Sanso, and at night, wrapped in mist and gas from the springs, it feels like bathing inside a cloud. Washing facilities are basic, so for a proper scrub use the indoor 'Sukawa-no-yu' (day visitors 9:00–16:00, separate fee), and if time allows try the natural-steam hut 'Oiran-buro' 100 m up behind the inn, where you lie on a straw mat and let the spring's steam envelop you. On some Wednesdays the big rotenburo closes from 15:00 until 6:00 the next morning for a water change and cleaning — check the official news page.
Season, prices and a Kurikoma itinerary
The season runs from early May to early November, tied to the opening of Route 342, with winter closure. Dainichi-yu is open 6:00–21:00 and the indoor bath to day visitors 9:00–16:00; some Wednesdays see cleaning closures. Aggregator listings give Dainichi-yu at ¥900 adults, ¥450 children (a 2025 report cites ¥800 — confirm on site); combined tickets with the indoor bath and hall-rest packages are available at the desk. Cash only; valuables lockers ¥100. By car it is about 1 h 10 min from Ichinoseki IC via Genbikei gorge; the seasonal bus from Ichinoseki Station runs only 2–3 times a day, so check the timetable. In late September to early October Mt Kurikoma's famous autumn colour — the 'carpet of the gods' — fills the car park from early morning. Compare it with Kurikoma Sanso across the road on the Akita side (same source, panoramic rotenburo), or combine with Genbikei and Ichinoseki's mochi cuisine for a full day. Note the self-catering wing is closed for now owing to snow damage (as of September 2026).
Before you go
- No official tattoo policy is published — ask at reception.
- Strongly acidic water — rinse off afterwards, avoid long soaks, and remove silver jewellery.
- Ryokan day-use hours are limited and may be suspended in peak season — phone the same morning.
- Open seasonally only — check the official site for operating dates before you go.
- Last entry is 30–60 minutes before closing.
Features
Mood & scenery
Price
Who with
Convenience
Amenities
✔ Verified operating: 2026-09 Operating status and rates cross-checked against the official site and onsen guides (full source notes in Japanese on the JA page)
Prices and hours change. Check official sources before visiting.
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