Teshikaga Town in eastern Hokkaido is known for Lake Mashu and Lake Kussharo, as well as being dotted with hot springs and is a town blessed with nature. Among all this rich nature, the biggest driving force behind the development of the town is Mount Iou. The dynamic sight of the powerful steam still rising from the volcano has made it a popular tourist spot. In this article, we'll introduce Mount Iou and unravel a little bit of its history. Mount Iou is only about 1.6 km away from JR Kawayu Onsen Station, and can be reached in about 2 minutes by car. Parking costs 500 yen, and you can use the Mount Iou Parking Lot and Lake Mashu First Observation Deck once each. By the way, it is open for free during the winter (late November to early April of the following year) when the park is closed, but please note that accidents and other troubles are at your own risk. Mount Iou is 512m above sea level and is classified as a lava dome with a rank C active volcano. As its name suggests, it is a mountain rich in sulfur, and in the Ainu language it is called "Atosanupuri," which means "naked mountain." The distinctive smell of sulfur hangs over the surrounding area, and sulfur crystals can be seen near the fumaroles. Sulfur is a high-quality mineral resource that attracted attention during the Meiji period, not only as a raw material for matches and gunpowder, but also as a means of acquiring foreign currency. Full-scale mining began in 1877, transportation routes were built, and it eventually developed into a major business. However, due to mass transportation that began in 1887, sulfur resources were quickly depleted. Mining finally came to a halt in 1896.

(Photo courtesy of Lake Mashu Tourism Association)

(Photo courtesy of Lake Mashu Tourism Association)

However, there is no doubt that Mt. Iou built a railway here and supported the development of the nearby Kawayu Onsen. Even now, the sight of billowing smoke rising from the mountainside is filled with overwhelming power, even if you are not aware of this history. It's on the way to Kawayu Onsen town, so why not stop by? <Cooperation> Lake Mashu Tourism Association Address: 3-3-1 Mashu, Teshikaga-cho, Kamikawa-gun, Hokkaido Phone: 015-482-2200 Official website: https://www.masyuko.or.jp