The Mashu Kussharo Trail (MKT)
The Mashu Kussharo Trail (MKT) showcases the dynamic landscape of the northern part of Akan Mashu National Park with a route that connects crater lakes, lava domes, and natural hot springs. The trail also visits sites such as Kussharo Kotan village, an important Ainu settlement, and Mt. Io (pronounced “ee-oh”), where natural sulfur was mined in the late nineteenth century.
The MKT route
The 61-kilometer MKT runs from the Mashu Caldera, overlooking Lake Mashu, to Bihoro Pass on the western rim of the Kussharo Caldera, with views over Lake Kussharo. The Nibushi Peninsula, on the eastern edge of Lake Kussharo, is around halfway along the trail. From here, heading west, the trail skirts Lake Kussharo, passing important Ainu sites, before winding up the inner slope of the Kussharo Caldera to the viewpoint at Bihoro Pass. Heading east, the trail winds around the Atosanupuri volcanic complex, through Kawayu Onsen, then on to the Mashu Caldera.
Around the lake
Lake Kussharo covers 79.3 km2 and is the largest of Japan’s caldera lakes. It fills most of the western half of the Kussharo Caldera, which is an enormous depression (20 × 26 km) that was formed in a series of major eruptions beginning more than 300,000 years ago. Ainu settlements flourished on the shores of the lake, where the people hunted, foraged, and fished. The MKT passes through Kussharo Kotan, the site of an Ainu village, and former Ainu hunting grounds such as the Wakoto Peninsula. Many points along the trail afford fine panoramas of the lake.
Volcanic foothills
The Atosanupuri volcanic complex covers the central area of the Kussharo caldera and consists of 10 lava domes. Mt. Io (512 m) is one of the tallest and most distinctive, with multiple fumaroles emitting plumes of steam and volcanic gases. The MKT leads along the base of Mt. Io, providing close-up views of some of its fumaroles. It follows a branching nature trail with signage (in English) introducing the vegetation and environment of the mountain.