The Chao III flow has a smaller volume of than Chao I and II. It has less ogives than Chao I and II and forms a single lobe, high. The flow overlies the pumice cone and parts of the Chao II on its eastern side. A lava dome formed above its vent and underwent several collapses, generating collapse scars. The flow is covered by weathering-derived aeolian debris from the other flows. This flow has a surface area of .
