Sunset Crater Volcano, as seen from up high on O'Leary Peak. Sunset Crater Volcano is the old cinder cone volcano that spewed lava and cinder over a wide area of this part of Arizona back in about 1065. The surrounding area is covered in cinder rubble, while two large lava flows emanate from the base of the Volcano. The one going west is called Bonito Flow, an approx 1-square mile of sharp basaltic lava with wonderfully odd formations, hornitos and voids. The Sunset Volcano Crater peak used to have a trail, but it has been closed to hikers since 1973 to protect against erosion.