Located along the north shore of the Big Island, Waimanu Valley is a gorgeous and special place to explore. But as often with beautiful places, adventuring into this part of Hawaii comes with some risks and challenges that are important to understand. The following is a quick look at what to know before making your way out to the trailhead.
The name “Waimanu” translates from the Hawaiian language into “bird water” or “river of birds.” It’s a well-earned name as the Waimanu Valley boasts several forested streams that are all home to a rich array of birds. Those streams come pouring over as waterfalls from massive cliffs before eventually coalescing into the one Waimanu Stream. These waterfalls and cascading waters further add to the area’s beauty. If you are an ornithophile, then the Waimanu Valley Hike may very well be worth the challenge.
The Waimanu Valley Hike is just about 16 miles round trip, with a total elevation gain of 7000 feet. This is a very challenging, and often dangerous, hike due to its steep inclines and high risks of rockfalls and flash flooding. Waimanu Valley is also inundated with mosquitoes. Such a combination of relentless mosquitos, steep hiking, rocky terrain, and frequent flooding make for a pretty unforgiving experience that many will want to pass on (and that’s okay! There are plenty of other fantastic hikes on the Big Island). You also will need to cross over a large stream that, depending upon rainfall, can often be wide and deep enough to be a river. Crossing it adds a “high likelihood of becoming wet” to the hike’s list of challenges.
This hike starts at the Waipio Valley Overlook, which you will find clearly marked at essentially the end of Highway 240 when you head west on it out of Honokaa. We say essentially because while the highway ends, another road does take its place. You will see a small paved road forking left where the road and parking area for the overlook forks are right. This paved road is advised as a residents-only vehicle road and non-locals should not attempt to take their vehicle down. In fact, due to its narrowness and incredibly steep grade with an average of 25%, most of the car rental agencies on the Big Island will cite you for an agreement violation if they find your rental vehicle has gone this way.
Instead, this road is the first part of the Waimanu Valley Hike that you will walk. Brace your knees as, again, this is an incredibly steep hill. You will walk about three-fourths of a mile before the road evens out and you can enjoy a more relaxing walk to a black-sanded beach. To complete the Waimanu Valley Hike, you will walk west along this beach and then cross over Wailoa Stream. Walk upriver as far as necessary in order to do this safely but note that there are no bridges or other types of water crossings.
Once you have crossed over, continue down the beach until you see a trail sign for “Muilwai Trail” and a dirt path leading up the steep cliffs bordering that western side of the beach. This first part up is going to be rough. Plan for about 1000 feet of vertical climbing across switchbacks. After the climb, however, is what most consider the most beautiful part of the trail. Here, you will get to enjoy hiking through a rich tropical landscape with lookout points for the ocean. You’ll cross about a dozen streams until finally reaching a vantage point for the valley and signs for the Waimanu Valley Campsite (primitive, backpacking-only campsite).
This hike will start feeling very remote once you reach the first beach. There are no homes or commercial buildings around. However, Waimanu Valley and Kohala Forest Reserve (where the first part of the Muliwai Trail is located) are popular helicopter fly-over zones. Expect to hear helicopters overhead about once an hour at a minimum throughout the day. If this heavy, regular noise bothers you, then consider a pass on this hike.
Before you go, the most important thing to do is check the forecast! Do not go after a rainstorm or whenever there is a 20% or greater rain forecast. This will help you avoid the risks of flash flooding. If it starts to heavily rain while you’re hiking, we recommend turning around.
-It is possible to camp at the Waimanu Valley Campsite, but it requires permitting. Do not attempt to backpack camp without one. You can normally obtain a camping permit via the state’s Division of Forestry and Wildlife website.
-As of this writing, camping is closed or limited to locals due to the need to renovate the aforementioned Waipio Valley Access Road (the paved road leading left from the highway’s end). The work for this is currently underway.