Onsen OniOnsen Oni

Unzen Sky Hotel

雲仙スカイホテルうんぜんスカイホテル

Lodging
Unzen Onsen
Kyushu & Okinawa·Nagasaki
0957-73-3345unzen-skyhotel.com

Day Use

Yes
11:30–16:00

Bathing & Water

Outdoor BathYes

Open-air outdoor bath

Indoor BathYes

Enclosed indoor bathing area

SaunaNo

Dry heat sauna room

OnsenYes

Uses natural hot spring water

Capabilities

Private BathYes

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

Mixed BathingNo

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

ParkingYes

On-site or nearby parking available

雲仙温泉(八幡地獄)

Unzen Onsen (Hachiman Jigoku)

Operated by · 雲仙スカイホテル

Sampled at wellhead
酸
Acidic
+ Iron-bearing · Sulfate
Classification

Aluminum-Hydrogen Sulfate spring

An acidic iron-bearing sulfate spring rising at Unzen's Hachiman Jigoku. At pH 3.4 the water is faintly sour and milky-white with a pale yellow cast, carrying the characteristic rotten-egg note of H₂S. Sulfate dominates the dissolved load, and a generous 184 mg/kg of metasilicic acid leaves a thin silica film that makes skin feel smoother afterwards.

Source temperature
26.1°C
Low temp.
Tonicity
1.08g/kg
Hypotonic
Free CO₂
6.90mg/kg
Low
Free H₂S
28mg/kg
Very high
Color
milky white with a faint yellow tint
Taste
faintly sour
Odor
faint hydrogen sulfide
Highlights
  • High silica
  • Sulfur-rich

Analyzed Sep 14, 2004·西部環境調査株式会社·Cert no. 第8472-1号・第8472-2号

About

Two bathhouses, Kinugasa no Yu (絹笠の湯) and Hakuun no Yu (白雲の湯), each with indoor and garden open-air sections. The sulfurous water is piped directly from Unzen Jigoku (雲仙地獄), the fumarole field just nearby, and flows continuously without recycling (kakenagashi, 源泉かけ流し). Gender assignments swap morning and evening, so overnight guests can use both sets. A private booking of the garden rotenburo plus main bath is available in a late-night slot.

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SM
Sergey M
2 years ago

A worn ryokan, stayed here for a night. As I understand it, they have day-use bathing too. There are two baths - one large indoor and through it an exit to a smaller outdoor one. The water is brown, no smell, standard temperature. The design is rather old-fashioned, but it was comfortable being there - it was already my sixth onsen of the day, but I didn't want to leave. Although maybe it's just that I like this type.