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Suicasmo, CC BY-SA 4.0
Iōzan (Atosanupuri Sulfur Mountain)
硫黄山（アトサヌプリ）Hokkaido
An active volcanic vent field near Kawayu Onsen where visitors walk within meters of hissing, sulfur-yellow fumaroles; hard-boiled eggs cooked in the natural steam are sold on-site.
- Crowd level
- Moderate
- Rating
- 4.5· 747 reviews
- Opening hours
- Daily 8:30 AM – 5:00 PM
- Admission
- Free entry; paid parking ¥500/car May 1-Oct 31 (free Nov-Apr); the parking ticket also doubles as valid parking at Lake Mashu Observatory #1.
- Nearest station
- Kawayu-Onsen Station (JR Senmō Main Line)
- Website
- masyuko.or.jp/enjoy/iouzan
Usual hours — confirm with the official site for holidays + seasonal closures.
Today
8:30–17:00¥500Stored weekly hours
Daily 8:30 AM – 5:00 PM
How to get there
~20 min walk (1.6km) or short taxi from Kawayu-Onsen Station to the visitor center/vent field.
Tags
volcanoonsenoff-the-beaten-path
Location
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