The Oboke Gorge has unusual geological strata, including a rudaceous schist formation designated as a natural monument. The Yoshino River has cut through the Shikoku Mountains over the ages, eroding crystalline schist into winding gorges with myriad shapes and forms, which almost look like marble statues. With fantastic reflections of cherry blossoms in spring and full autumn color in season, the river is host to a number of boating activities, from relaxing cruise down the calm part of the river, to an exciting rafting trip down the rapids. Koboke lies 3km downstream of Oboke and its scale is a little modest than Oboke, but is still beautiful and fascinating because of the rare shaped rock and its beauty of sandstone.