Mount Tantalus (Puʻu ʻōhiʻa)[1]: 581, 583, 931  is an extinct cinder cone in the southern Koʻolau Range on the Hawaiian Island of Oʻahu.

It had "rugged canyons, wooded valleys, aromatic eucalyptus giants, stag-horn fern, pungent guava", monkeypod, shower cassias, and myrtle, with a two-room, corrugated-roofed "Half-Way House", managed by 1900s forester David Haugh, offering a welcome stop for trekkers.

[1]: 581  Many immigrant families of note settled there "in cool picturesque seclusion", including the Waterhouses, Giffords, Wilders, Dickeys, Davies, Isenbergs, Browns, and Alexanders.

The southern slope of Tantalus was bombed in Operation K, Japan's unsuccessful second attack on Oʻahu, which took place March 4, 1942.

Today, Tantalus is a popular destination for hikers, road bicyclists, and skateboarders as well as one of the most frequented tourist spots on Oʻahu.