Mount Kusatsu-Shirane in Gunma Prefecture is an active volcano with an elevation of 2,160 meters and is well known for its crater lake with emerald green water. Volcanic gases dissolve into the water, giving it a unique color, and the water is highly acidic, easily dissolving iron. There are hiking trails that take you from the desolate, treeless land to the lush green hillsides covered with alpine plants.
Kusatsu Onsen boasts the largest amount of natural spring water in Japan and is one of the three most famous hot springs in Japan. Centered on the landmark Yubatake, where hot water flows vigorously, the hot spring town, which has built up its history and tradition, is still bustling with activity. Mount Kusatsu-Shirane, which produces a rich source of hot spring water, and the Zoo and Botanical Garden, which uses hot spring heat to recreate a subtropical climate, are just a few of the many unique attractions.