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HOME > Japan’s Local Treasures > Atosa-Nupuri Volcano Trekking Tour
Feel the heartbeat of the Earth as you explore an off-limits active volcano
Lake Mashu Tourist Association
Atosa-Nupuri, also known as Mt. Io, is an active volcano located at an altitude of 508m above sea level in Hokkaido's Akan-Mashu National Park. Atosa-Nupuri means “Bare Mountain” in the indigenous Ainu language, a name that perfectly reflects its dramatic landscape of rocks and sparse vegetation. The Japanese name Mt. Io literally means “Sulfur Mountain,” as the area was used as a sulfur mine from 1877 to 1963.
Atosa-Nupuri has more than 1,500 fumaroles, which emit smoke plumes and make a rumbling sound. The air is filled with the smell of sulfur, and bright yellow sulfur crystals dot the rugged terrain. As you stand in front of the mountain, you can feel the heartbeat of the Earth in this dynamic sight. The crater trace of Kumaotoshi, which was created by a phreatic explosion several hundred years ago, is one of the biggest highlights.
Visitors can enjoy the nature trail at the foot of Atosa-Nupuri, but the climbing route to the mountain is only accessible when accompanied by a certified guide from Teshikaga Town. This route had long been closed and finally reopened in 2021 through a three-year process. The trekking path starts from the forest road at the site of the old Yasuda Railway track. After passing the remains of a sulfur mine, the trail will lead you to a sand and gravel mountain with no vegetation. You will climb up a certified peak at 337m above sea level and then go down with a close-up view of the fumaroles.
The entire course takes about 3 hours and is available from June to around October. For more information on the trekking tour, please contact Lake Mashu Tourist Association.
How to get there
From Kushiro Airport, take the shuttle bus to Kushiro Station (45 minutes), then the JR Senmo Line to Kawayu Onsen Station (90 to 110 minutes). The tour meeting point is at Mt. Io Rest House, 20 minutes on foot from Kawayu Onsen Station.
Mt. Io Rest House
Kawayu Onsen, Teshikaga-cho, Kawakami-gun, Hokkaido
