Pu'uka'oku Falls, Tiered waterfall on Molokai Island, United States.

Puʻukaʻōkū Falls drops about 840 m down a near-vertical basalt cliff on Molokai's north coast, 500 m east of ʻOloʻupena Falls. It is an intermittent waterfall: water flows only after rain, sliding down the rock rather than falling freely, and strong winds push the water back upward before it reaches the sea.

The falls begin at about 850 m on the cliffs of Molokai's north coast, 500 m east of the 900 m ʻOloʻupena Falls. Sources record its 840 m drop as the second-highest waterfall in the United States and the eighth-highest in the world. No road or marked trail reaches it; the usual approach is by sea.

The name Puʻukaʻōkū is written with ʻokina (glottal stops) and kahakō (macrons) in Hawaiian orthography, marks often dropped in English renderings such as Pu'uka'oku. The falls sit about 500 m east of the 900 m ʻOloʻupena Falls on Molokaʻi's north cliffs, in the same roadless, densely vegetated tract reached only by sea.

The waterfall is best seen from the water by boat or kayak, as the cliffs and dense undergrowth make access on foot almost impossible. Anyone visiting by water should pay close attention to local weather and sea conditions before setting out.

Despite its exceptional drop of around 840 meters (about 2,760 feet), the waterfall is virtually invisible from land, hidden behind cliffs and forest. This makes it one of the most difficult to reach waterfalls of its scale anywhere in the world.