Hi'ilawe Falls is the most famous waterfall in Waipio Valley. The falls is between 1,200 and 1,600 feet tall (depending on who you ask), making it the tallest waterfall in the state of Hawaii. It was a lava flow from Mauna Kea that formed the cliffs on the side of the falls. Hi'ilawe Falls share the same cliff wall with the often dry Hakalaoa Falls. Lalakea Stream above the brink of Hi'ilawe Falls had been partially dammed to provide water for developments in the area. Apparently the dam is now no longer required, but still exists, and many local groups are trying to get it removed so the falls can revert back to their original state.
Hi'ilawe Falls is located inside Waipio Valley and is only visible from the valley or from the air. If you hike down into the valley, the waterfall is visible via a 5-10 minute walk along the road to the left. DO NOT hike beyond the falls, as this is private property. Do not attempt to drive ANY car into the valley. The road descends 900ft in a mile and is one of the world's steepest roads. Hike it only, just be prepared for the long hard climb back out.