The hike down to Waipi‘o and over the pali to Waimanu Valley is considered by many one of the top three treks in Hawaii. You must be fully prepared for camping and in excellent condition to attempt this hike. Also, water from the streams and falls is not good for drinking due to irrigation and cattle grazing topside; hikers should bring purification tablets or boil or filter it to be safe. To get to Waimanu Valley, a switchback trail, locally called the Z trail but otherwise known as the Muliwai Trail, leads up the 1,200-foot pali, starting about 100 yards inland from the west end of Waipi‘o Beach. Although not long, this is by far the most difficult section of the trail. Waimanu was bought by the State of Hawaii some years ago, and it is responsible for trail maintenance.
The trail ahead is decent, although it can be muddy, but you go in and out of more than a dozen gulches before reaching Waimanu. In the third gulch, which is quite deep, a narrow cascading waterfall tumbles into a small pool right at trailside, just right for a quick dip or to dangle your feet. Another small pool is found in the fifth gulch. After the ninth gulch is a trail shelter. Finally, below is Waimanu Valley, half the size of Waipi‘o but more verdant, and even wilder because it has been uninhabited for a longer time. Cross Waimanu Stream in the shallows where it meets the sea. The trail then continues along the beach and back into the valley about 1.5 miles, along the base of the far side, to Wai‘ilikahi Falls, some 300 feet high. For drinking water (remember to treat it), walk along the west side of the pali until you find a likely waterfall. The Muliwai Trail to the Waimanu Valley floor is about 15 miles round-trip from the trailhead at the bottom of the pali in Waipi‘o Valley, or 18 miles round-trip from Waipi‘o Lookout.
Regardless of how long it takes you to complete this hike, it’s quite the badge of honor. Some have been known to finish it in 24 hours and others take a few leisurely days at normal hiking speed. To stay overnight in Waimanu Valley, you must have a camping permit available through the Division of Forestry and Wildlife; permits are for up to six people ($12 residents, $18 non-Hawaii residents). Before you go, check the news release section of the Division of Forestry and Wildlife website to make sure that the trail is not closed due to hazardous conditions such as rain and/or mud.