Funai Onsen

府内温泉ふないおんせん

Other
Kyushu & Okinawa·Oita

Day Use

Yes

Bathing & Water

OnsenYes

Uses natural hot spring water

府内温泉

Funai Onsen

Operated by · 株式会社サイエンス

Sampled at wellhead
Bicarbonate
Classification

Sodium spring

A sodium-led bicarbonate spring — the classic jūsō-sen (soda-water) style, weakly alkaline and soft on the skin, placing it in Japan's beauty-water family. The source emerges hot at over 51 °C; the water is medium yellow-brown and clear with a moderate mineral note. A generous 198 mg/kg of metasilicic acid leaves the kind of silica film that makes skin feel noticeably smoother afterwards.

pH
8.60
Weakly alkaline
Source temperature
51.2°C
Hot
Tonicity
1.25g/kg
Hypotonic
Flow rate
700L/min
High
Radon
7.40Bq/kg
Low
Color
medium yellow-brown and transparent
Taste
tasteless
Odor
moderate mineral odor
Highlights
  • High silica
  • Top-decile hot

Analyzed Sep 30, 2021·公益社団法人大分県薬剤師会検査センター·Cert no. 大薬第 72-21060010号

Programs

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SM
Sergey M
1 year ago

458. Funai Onsen, Oita Onsen for 640. Operating hours listed as 14:00 to 23:00 (except Tue). They stamp the 88 Onsen of Kyushu book. Bath photos from the internet, accurate. Two baths inside, the water is black-brown. The water color shifts depending on conditions. When there's a lot of it without any objects, it looks black. When there's less, it looks more brown. When your body is in the water, the upper part looks red-black through the surface, and when submerged deep (like placing your hand on the bottom), you can't see your hand at all. Temperature 39-40 and 41. Air inside is fine. Has a sauna and cold bath. Interesting place, primarily because of the rare black water. 31.03.2025