Olo'upena Falls, United States
The fourth-highest waterfall in the world, Olo'upena Falls, is the second waterfall on our list found on the remote Hawaiian island of Moloka'i. The Olo'upena Falls, like Pu'uka'oku Falls (No. 8 on our list), are located on the isolated northeastern shore of the island.
At 2,953 feet (900 meters), Olo'upena Falls is a tiered, ribbon-thin stream plunging over the side of one of the world's tallest seaside cliffs, Haloku Cliffs -- the same cliffs that Pu'uka'oku Falls originate from. Surrounded by huge mountains on either side, this magnificent waterfall is so remote that there are no access trails to reach it; like Pu'uka'oku Falls, it is only accessible by air or sea. The best time to view Olo'upena Falls is during the rainy season (November through March), and numerous guided boat and aerial excursions offer breathtaking views of the falls plummeting over the vertical cliff face directly into the sea [source: Pavils].