Mount Tantalus (Puu-ohia), is an extinct cinder cone in the southern Koʻolau Range on the Hawaiian Island of Oʻahu. It also has a summit crater, Tantalus Crater. The cinder cone formed after the demise of Koʻolau Volcano, during a time of rejuvenated stage volcanism in southeastern Oʻahu that also formed Punchbowl Crater, Diamond Head and Koko Head.