Mt. Io (Atosanupuri)
Feel the Raw Power of the Earth
Witness the dramatic steam and vibrant sulfur crystals of an active volcano.
Mt. Io, also known as Atosanupuri, is an active volcano and the source of Kawayu Onsen’s healing waters. Countless vents release thick white steam, filling the air with the earthy scent of sulfur. Here, you can stand close to volcanic activity and feel the earth’s energy firsthand.
In Ainu, Atosanupuri means “naked mountain,” reflecting its stark appearance. Once a sulfur-mining site, its rugged brown slopes remain largely free of vegetation, creating an otherworldly landscape. The deep rumble of steam rising from the earth is a reminder that the volcano is still alive. Feel warmth radiating from the ground and drifting steam on your skin. Bright yellow sulfur crystals coat the rocks, contrasting vividly with the dark volcanic soil.
At the foot of the mountain, Ezo Isotsutsuji (marsh tea) blooms in delicate white clusters from June to July, creating a striking contrast with the rugged terrain. The Tsutsugahara Nature Trail connects Kawayu Onsen with Mt. Io, while guided tours offer insights into the area’s geology and ecosystem.
- * Please note that the text shown on this page includes machine translations.
- Category
- With friends
- Shopping
- Solo trip
- Guys' trip
- Girls' trip
- Couple
- Family
- Travel style
- Souvenirs
- Animal habitats, plant habitats
- Mountain, ridge, plateau, marshland, canyon
- Natural scenery, spectacular views
- Travel Inspiration
- Enjoy spectacular views
- Best for a girls' trip
- Nearest airports
General Information
- Postal code
- 〒088-3461
- Address
- 北海道川上郡弟子屈町硫黄山
- Telephone Number
- 015-483-3511（Iouzan Rest House）
- Open
- 8:30-17:00
- Closed
- Open all year round
- Car Park
- 150 spaces, charged
- Directions
- ●By car: About 5 minutes from JR Kawayu Onsen Station
●By car: About 140 minutes from Doto Expwy Ashoro IC - Website
- Remarks
- *Hours and closed days are subject to change. Please check the official website
* Information on facilities is subject to change. Please check each official website for the latest information.
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