Mount Iō also Mount Iwo is an active andesitic stratovolcano on the Shiretoko Peninsula of Hokkaidō, Japan. It sits within the borders of the town of Shari. Mount Iō is known for erupting liquid sulphur in the eruptions of 1889 and 1936. Mount Iō literally means, sulphur mountain. There are two explosion craters and a lava dome at the summit of the volcano.