The Pipiwai Trail runs up the 'Ohe'o streambed, rewarding hikers with perfect views of the upper waterfalls. The trail starts on the mauka side of the visitor center and leads up to Makahiku Falls (0.5mi/800m) and Waimoku Falls (2mi/3.2km). Or take a little shortcut by picking up the trail from the pedestrian crossing at the highway. To see both falls takes about two hours return. The upper section is muddy, but boardwalks cover the worst bits.
Along the path, you'll pass large mango trees and patches of guava before coming to an overlook after about 10 minutes. Makahiku Falls, a long bridal-veil waterfall that drops into a deep gorge, is just off to the right. Thick green ferns cover the sides of 200ft (60m) basalt cliffs where the fall cascades - a very rewarding scene for such a short walk.
Continuing along the main trail, you'll walk under old banyan trees, cross Palikea Stream (killer mosquitoes thrive here) and enter the wonderland of the Bamboo Forest, where thick groves bang together musically in the wind. Beyond them is Waimoku Falls, a thin, lacy 400ft (120m) waterfall dropping down a sheer rock face. When you come out of the first grove, you'll see the waterfall in the distance. Forget swimming under Waimoku Falls - its pool is shallow and there's a danger of falling rocks.
If you want to take a dip, you'll find better pools along the way. Shortly before Waimoku Falls, you'll cross a little stream. If you go left and work your way upstream for 10 minutes, you'll come to an attractive waterfall and a little pool about neck deep. There's also an inviting pool in the stream about halfway between Makahiku and Waimoku Falls.