The highlights of the Hachinoyama Volcano Geosite are Hachinoyama Volcano and the picturesque and artful landforms created by lava that flowed from it. hachinoyama erupted about 36,000 years ago and is one of the largest scoria cones of the Izu Tobu Volcano Group (second only to Omuroyama Volcano).
Parts of lava, which flowed out of the Hachinoyama Volcano, have flowed along the present Saganogawa River. There is a track starting from the point where Saganogawa River intersects with Route No. 135 that follows along the river. Along this track, one can see the beautiful sight of the river flowing over the lava that came down from Hachinoyama Volcano, and the columnar joints formed when the lava was cooling down and hardening.