Nagasaki · Shimabara Onsen
Hotel Seaside Shimabara (Shimabara Onsen & Carbonated Spring)
HOTELシーサイド島原 島原温泉・高濃度炭酸泉
An inn with a sixth-floor panoramic great bath over the Ariake Sea and an open-air bath in the main building. Two springs, a carbonated one at 1,800–1,900 ppm and Shimabara Onsen, for ¥800 as a day visitor.
- Price (adult)
- ¥800
- Hours
- 12:00–23:00 (last entry 22:00)
- Closed
- Irregular closures (check ahead)
- Access
- Shinminato, Shimabara, Nagasaki (on the Ariake Sea, near Shimabara Port)
- Water type
- Bicarbonate spring
- Tattoos
- Ask ahead
- Admission
- Day bathing is ¥800 for adults and ¥400 for children. Towels are sold for ¥200, and a book of ten tickets costs ¥6,000.
- Hours
- The main-building bath runs 12:00–23:00 (last entry 22:00), and the new-building panoramic bath 6:00–12:00 and 15:00–23:00 (last entry 22:00). The two differ in hours, so check before you go.
- Spring quality
- The source is in Shimokawashiri-machi, Shimabara, and the spring is a carbon-dioxide-bearing magnesium, calcium and sodium bicarbonate spring. Carbonation is given as 1,800–1,900 ppm; source temperatures are 26.0 °C for the carbonated spring and 42.0 °C for Shimabara Onsen.
- Facilities
- The hotel has a panoramic great bath, an open-air bath, a sauna and a rest room. Shampoo and the like are provided at the washing stations; towels are for sale.
- Phone
- 0957-64-2000
- Official site
- seaside-shimabara.com ↗
- Open in Google Maps
- Google Maps ↗
Essentials
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Why go
- Carbonated spring at 1,800–1,900 ppm
- Sixth-floor bath overlooking the Ariake Sea
- Open-air bath and sauna in the main building
By Shimabara Port, a hotel with two springs
Hotel Seaside Shimabara stands in Shinminato, Shimabara, facing the Ariake Sea. It has two springs: Shimabara Onsen, and a carbonated one rich in dissolved gas. From the sixth-floor great bath the sea and sky open up, while the main building's bathhouse holds an open-air bath and a sauna. Day bathing is accepted, and ¥800 covers both springs.
The rarity of a carbonated spring
The draw here is the carbonated spring at 1,800–1,900 ppm. Its source is in Shimokawashiri-machi, Shimabara, and at 26.0 °C it is on the cool side; a long soak in lukewarm water brings fine bubbles onto the skin, the classic sensation of a carbonated bath. Shimabara Onsen, at 42.0 °C, is the choice when you want warmth, and alternating between the two gives you both a cool and a hot bath.
Practical notes: the hours differ by bath
As a day visitor, mind that the hours differ by bath: the main-building bath runs 12:00–23:00 (last entry 22:00), the new-building panoramic bath 6:00–12:00 and 15:00–23:00 (last entry 22:00). For the sea at dusk, take the sixth-floor bath; for a slow open-air soak with a sauna, take the main building. Towels are sold for ¥200 and shampoo is provided, and a rest room lets you sit a while after bathing.
Before you go
- No official tattoo policy is published — ask at reception.
- Ryokan day-use hours are limited and may be suspended in peak season — phone the same morning.
- Payment is usually by ticket machine in cash — bring coins.
- Last entry is 30–60 minutes before closing.
Features
Sauna & wellness
Mood & scenery
Price
Who with
Amenities
✔ Verified operating: 2026-10 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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