Mt. Io

A Former Sulfur Mine and the Source of Kawayu Hot Spring.

Mt. Io (Atosanupuri), a once-prosperous active volcano due to sulfur mining, is the source of the hot spring waters of Kawayu Hot Spring. Countless fumaroles dot its brown mountainside, powerfully emitting white smoke containing sulfur. The air is thick with the scent of sulfur, and you can get very close to these fumaroles, allowing you to experience their dynamism firsthand.

Spreading at the foot of the mountain is a large colony of "Ezoisotsutsuji" (Hokkaido rhododendron), a species unique to Hokkaido. Growing in the harsh environment, it blooms beautiful pure white flowers from June to July. The "Tsutsujigahara Nature Exploration Trail" is maintained from the town of Kawayu Hot Spring to Mt. Io, and guided tours are also available.

  • * Please note that the text shown on this page includes machine translations.
Nearest airports
New Chitose Airport Sapporo Okadama Airport Hakodate Airport Okushiri Airport Asahikawa Airport Wakkanai Airport Rishiri Airport Okhotsk Monbetsu Airport Memanbetsu Airport Nemuro Nakashibetsu Airport Tancho Kushiro Airport Tokachi Obihiro Airport

General Information

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
*Hours and closed days are subject to change. Please check the official website
Closed
Open all year round
Prices
Free admission
Car Park
150 spaces, Regular cars: 500 yen
Directions
●On foot: About 20 minutes from JR Kawayu Onsen Station
●By car: About 5 minutes from JR Kawayu Onsen Station
●By car: From Doto Expwy Ashoro IC via Route 241 and 391, 120 km, About 140 minutes
Website

Official site (Japanese)

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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