Mount Tantalus (Puʻu ʻōhiʻa) 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 as part of the Honolulu Volcanics. Tantalus overlooks the modern city of Honolulu, which is built on top of Tantalus cinders.