When Mount Usu erupted in March and April 2000, over 60 new craters opened up on the west side of the mountain, expelling huge amounts of smoke several kilometers into the sky and destroying nearby buildings and roads. Today, the area can be viewed from several walking trails.
The Kompirayama Walking Trail starts at the Toyako Visitor Center in Toyako Onsen and leads to the Nishiyama parking lot. Along the way, you can see various ruins, including a destroyed public bath house, apartment block and bridge. The trail also passes two of the largest craters from the 2000 eruption, as well as large erosion control dams. It takes about 40 minutes to complete the walk.
From the Nishiyama parking lot, the Nishiyama Crater Walking Trail leads to some more of the newly created craters around Mount Nishiyama. Several destroyed buildings, disrupted roads and broken phone poles have been left untouched for visitors to witness the destructive power of the volcano. It is about a ten minute walk from the parking lot to the craters and a further ten minute walk to the trail's southern end, where the ruins of a kindergarten and a second parking lot are located.
Furthermore, there is a paid observatory on top of Mount Kompirayama, which provides panoramic views over Lake Toya and the new craters on the west side of Mount Usu. The observatory is commonly accessed by car (1000 yen per car including passengers), but can also be reached on foot (1000 yen per group of up to four pedestrians). Like the walking trails, the observatory is closed in winter.
The trailhead of the Nishiyama Crater Walking Trail is located a five minute car or bus ride from Toyako Onsen. From Toyako Station, take a bus bound for Toyako Onsen (洞爺湖温泉) and get off at Nishiyama Yuhodo (西山遊歩道, 280 yen one way, about 15 minutes, one bus per hour).