Mount Usu (有珠山, Usuzan) is a volcano which has erupted four times in the past 100 years. Its most recent eruption occurred in the year 2000.

The Usuzan Ropeway brings you close to the volcano's summit. The upper station's observation deck offers panoramic views of Lake Toya and neighboring Showa Shinzan. From a second observation deck a short walk away, there are views of the ocean and Mount Usu's largest crater, which was formed in an eruption in 1977.