The Tanizawa River formed the Todoroki Ravine. The ravine was formed by the Yazawa River as it heads for the Tama River. It is the only ravine and valley in Tokyo - stretching along a one kilometer course along a path where visitors can view waterfalls, bridges and rock formations along the way. Todoroki Valley also has a natural water spring. Todoroki Ravine Park is more of an adventure stroll than a typical Japanese park, despite its name.