Mount Io (Shiretoko)1,562 m

About Mount Io (Shiretoko)

Mount Io (Shiretoko) is a 1,562 m mountain in Shari Town, Hokkaido. It lies within Shiretoko National Park. The largest stratovolcano on the Shiretoko Peninsula. A crater on its northwest flank has repeatedly erupted molten sulfur, a style of eruption rare anywhere in the world. In 1935-1936 it poured out about 200,000 tons of sulfur, turning the Kamuiwakka River and the shore yellow. The crater still releases fumes.

Sources: GSI, Elevations of Major Mountains in Japan, MLIT, National Land Numerical Information: Natural Park Areas, Japan Meteorological Agency, Shiretoko-Iozan, Ministry of the Environment, Shiretoko National Park: Highlights (sources in Japanese)

Mountain data

Elevation

1,562 m#49 of 156 by height

Elevation basis

Triangulation pointGeospatial Information Authority of Japan, Elevations of Major Mountains in Japan (March 31, 2026)

Japanese name

硫黄山（いおうざん）

GSI name / other name

知床硫黄山

Location

Shari Town, Hokkaido

Area

Okhotsk

Natural park

Shiretoko National Park

Active volcano

Part of Shiretoko-Iozan

100 Famous Japanese Mountains

None

Hokkaido Hyakumeizan

Both editions (No. 34 in 2003)

The location lists the municipality of the summit and any others within 300 m of it (checked with the GSI reverse geocoder).

Themes that include Mount Io (Shiretoko)

• Hokkaido 100 Mountains
• Active volcanoes
• Shiretoko National Park