For expert trekkers only, this 8.5-mile backcountry trail goes from Waipiʻo Valley to Waimanu Valley, traversing steep, slippery and potentially treacherous ground. It takes 6½ to eight hours one way and crosses 13 gulches – brutal to ascend and descend, but lovely, with little waterfalls and icy pools for swimming. Plan on camping in Waimanu Valley for at least two nights. For safety reasons, do not attempt this hike during or after rains. For detailed hiking information, contact Na Ala Hele ( in Hilo.

You can park your car at the signposted 24-hour parking area. The Muliwai Trail begins at the base of the cliffs on the far side of the valley; you can see it zig-zagging up the cliff face as you approach. A shaded path at the end of the beach takes you to a dual trailhead: head right and up for Muliwai (straight ahead leads to the King’s Trail). The ancient Hawaiian footpath now rises over 1200ft in a mile of hard laboring back and forth up the cliff face; it’s nicknamed ‘Z-Trail’ for the killer switchbacks. Hunters still use this trail to track feral pigs. The hike is exposed and hot, so cover this stretch early.

Eventually the trail moves into ironwood and Norfolk pine forest, and tops a little knoll before gently descending and becoming muddy and mosquito-ridden. The view of the ocean gives way to the sounds of a rushing stream. The trail crosses a gulch and ascends past a sign for Emergency Helipad No 1. For the next few hours the trail finds a steady rhythm of gulch crossings and forest ascents. A waterfall at the third gulch is a source of fresh water; treat it before drinking. For a landmark, look for Emergency Helipad No 2 at about the halfway point from Waipiʻo Beach. Beyond that, there’s an open-sided emergency shelter with pit toilets and Emergency Helipad No 3.

Rest at Helipad No 3 before making the final difficult descent. Leaving the shelter, hop across three more gulches and pass Emergency Helipad No 4, from where it’s less than a mile to Waimanu Valley. This final section of switchbacks starts out innocently enough, with some artificial and natural stone steps, but over a descent of 1200ft the trail is poorly maintained and hazardous later. A glimpse of Waiʻilikahi Falls (accessible by a 45-minute stroll) on the far side of the valley might inspire hikers to press onward, but beware: the trail is narrow and washed out in parts, with sheer drop-offs into the ocean and no handholds apart from mossy rocks and spiny plants. If the descent is questionable, head back to the trail shelter for the night.

Waimanu Valley is…well, this is as good as God's green Earth gets. It's a mini Waipiʻo, minus the tourists. There was once a sizable settlement here, and the valley contains many ruins, including house and heiau terraces, stone enclosures and old loʻi. In the early 19th century an estimated 200 people lived here, but the valley was abandoned by its remaining three families after the 1946 tsunami. Today you’ll bask alone amid a stunning deep valley framed by cliffs, waterfalls and a boulder-strewn beach.

From the bottom of the switchbacks, Waimanu Beach is 10 minutes past the camping regulations signboard. To ford the stream to reach the campsites on its western side, avoid the rope strung across the water, which is deep there. Instead, cross closer to the ocean entry where it is shallower. Camping requires a state permit from the Division of Forestry & Wildlife for a maximum of six nights.

There are nine campsites: recommended are No 2 (full valley views, proximity to stream, grassy spot), No 6 (view of Waiʻilikahi Falls, access to the only sandy beach) and No 9 (very private at the far end of the valley, lava-rock chairs and a table). Facilities include fire pits and composting outhouses. There’s a spring about 10 minutes behind campsite No 9, with a PVC pipe carrying water from a waterfall; all water must be treated.

On the return trip, be careful to take the correct trail. Walking inland from Waimanu Beach, don’t veer left on a false trail-of-use that attempts to climb a rocky stream bed. Instead keep heading straight inland past the camping regulations sign to the trail to the switchbacks. It takes about two hours to get to the trail shelter, and another two to reach the waterfall gulch: refill your water here (again, treat before drinking). Exiting the ironwood forest soon after, the trail descends back to the floor of Waipiʻo Valley.