The Muliwai Trail is a very challenging hiking trail which connects Waipio Valley to Waimanu Valley and features breathtaking views of waterfalls, beaches, lakes, streams, and the coast.  Difficulties encountered on the hike are numerous and are outlined below in the next section.  Read it to become familiar with the safety hazards and ensure that you are well prepared and can handle the hike.  Route maps and GPS coordinates are not provided because this is an official trail which is (minimally) maintained by the State of Hawaii -- Division of Forestry and Wildlife.  All hikers should obtain complete information on the hike and current conditions from the above entity.
Upon finishing up our trip to Kauai in February of 2014, we decided to make plans to return to Hawaii and visit the Big Island in February of 2015.  Once the plane tickets were purchased, the long process of choosing one or two major hikes to carry out during the trip began.  One hike which caught my attention was the Muliwai Trail which connects Waipio Valley to Waimanu Valley.  Waipio Valley is the easternmost valley of the North Kohala Coast Valleys.  I read several trip reports online from those who had taken the hike and they all described it as challenging but beautiful.  In my research, I also noted that the Muliwai Trail had some similarity to the Kalalau Trail but also some key differences.  As for the similarities, the Muliwai Trail and Kalalau Trail are both hikes along the coast overlooking the ocean which wind into and out of multiple small valleys (or gulches) with stream crossings and contain areas of steep elevation gain.  The main difference, and this was very important to me, is that the Muliwai Trail has less of an element of danger to it.  Since my hike of the Kalalau Trail one year ago, several more hikers have lost their lives while on that trail -- one person by falling off the edge and a couple others by being swept away while trying to cross streams that were flooding.  In view of these developments, I considered removing my Kalalau Trail report from the internet.  But then I realized that since the hike takes place within a State Park along an official trail, hikers (both prepared and unprepared) are going to do the hike regardless.  Thus, I figured that perhaps my report actually helps to increase safety awareness and serves a beneficial purpose for those considering the hike.  Getting back to the Muliwai Trail, the big difference with this hike is that there is far less exposure along cliffs while hiking.  There are a few sections where caution is definitely in order, such as along the Z-Trail climb out of Waipio Valley, but there is nothing like the sheer drops into the ocean as found along the Crawler's Ledge and Eroded Cliffs sections of the Kalalau Trail.  As far as safety concerns along the Muliwai Trail, the DF&W (Division of Forestry and Wildlife) lists the following:  (1) rainy weather, (2) drinking water quality, (3) centipede bites, (4) trail conditions, and (5) avoiding hunters.  Let me try to discuss these five safety concerns in a little bit more detail.  (1) Rainy weather can definitely change this route from a challenging hike into a dangerous hike.  The DF&W notes that "this region of the Big Island receives over 100 inches of rain annually.  Heavy rains regularly cause flash floods which can make attempted stream crossings potentially fatal."  At nearly every stream crossing along the trail, there are warning signs alerting hikers to this danger.  Rainy weather can also create muddy conditions on the trail, cause rockfall from above, result in falling branches and trees, and cause high surf to flood beaches and campgrounds.  (2) Leptospirosis (sometimes shortened to Lepto) and Hepatitis are potential threats, entering the water upstream of stream crossings and making the water unsafe to drink without proper treatment.  Lepto is usually caused by rats or pigs and can get into someone's body through open cuts or sores when swimming or through the mouth when drinking.  Using a water filter alone does not guarantee that Lepto will be removed from any drinking water that you pump out of streams.  This is because of the small size of the bacteria (less than 1 micron in diameter).  So in addition to filtering, the water should also be treated or boiled to make it 100% safe.  It should be noted that there were 28 cases of Leptospirosis which originated from the Waipio River during a recent 10 year period.  Carrying out this hike requires a mandatory crossing of the Waipio River.  Thus, if you have cuts or open sores on the lower half of your body, it is probably best not to do this hike.  (3) Centipedes can be found along the trail and in the Waimanu Valley camping areas.  According to the DF&W, centipedes are usually noted "in the rocks and leaf litter" and may "seek shelter in your tent and bedding".  I came across one of the centipedes along the trail and you will see a picture of it within the report.  It looked somewhat fearsome and I would not have wanted it crawling on me or biting me.  It is said that the bite is painful but not extremely dangerous.  Apparently, the venom that a centipede releases during a bite is not toxic to humans but could potentially cause allergic reactions in some people.  (4) The trail conditions will vary a lot depending on recent weather.  The DF&W notes that the trail is only "minimally maintained" and that it is "steep, deeply eroded in places, rocky, muddy, and slippery when wet."  My hike took place during a time of dry weather and my only real concern was dealing with the steepness of the ascents out of valleys.  If the trail is muddy and slippery during a hike, a trekking pole can help to minimize the amount of falls.  (5) The trail is open year round for game mammal hunting, although there were no hunters to be seen during my hike.  However, it is probably best to stay on the trail, make noise while hiking, and wear bright colors so that any potential hunters do not mistake you for prey.
Warning sign about the danger of falling rocks --
Warning sign about hazardous cliffs --
Warning sign about flash flood dangers --
In preparing for my hike to Waimanu Valley at home, I intended to do it as an overnight backpacking trip.  The actual hiking mileage on the Muliwai Trail is 15.3 miles RT.  However, if you do not have a 4WD vehicle, the hike becomes about 19 miles RT, because you must start at the Waipio Valley lookout, rather than at the Waipio River crossing.  At home, I packed up all of my backpacking gear and brought it with me to the Big Island on the plane.  Upon arrival, though, I was unable to obtain butane fuel for my backpacking stove at any store in Kailua-Kona.  And I checked several stores looking for it, including a large sporting goods store.  In view of this, I decided to switch it to a day hike, something which is rarely done by people.  Remembering the foolishness of hiking the Kalalau Trail as a day hike last year, I was worried that I would be making the same mistake with the Muliwai Trail.  So I decided to set a definite turn-around time.  I figured that my minimum goal would be to make it to an overlook point of Waimanu Valley, while still keeping the main goal of actually reaching the Waimanu black sand beach.  I left the Waikoloa Hilton where we were staying at 5:00am and began the hike by flashlight at the Waipio Valley lookout parking area at 6:20am.  Because I did not have a 4WD vehicle, I had to hike down the extremely steep Waipio Valley Road.  This road is considered to be the steepest road of its length in the United States with a grade that varies from 25% to 45%.  It is said that the Waipio Valley Road burns out brakes on the way down and stalls engines on the way up.  But the only thing it did to me was put pressure on my knees and cause the hike to start out with a bit of pain.  Upon reaching the valley floor, I turned right and walked along a gravel road with deep mud puddles until I reached the parking area for Waipio Beach.  From there, I had to cross Waipio Stream.  I had read accounts online of hikers who had to cross Waipio Stream by either swimming or wading in water up to their shoulders.  But crossing near the spot where the incoming surf met the outgoing stream, the water was only about halfway up to my knees.  This was no doubt helped by the fact that it was low tide and there was a low stream level due to the lack of recent rains.  Once across Waipio Stream, I put my hiking boots back on and enjoyed a peaceful walk across the black sand of Waipio Beach.  Looking in front of me, I could see the intimidating Z-Trail portion of the Muliwai Trail fast approaching.  Looking behind me, I had nice views of Kaluahine Falls plunging into the ocean.  Eventually, the sand turned to rocks with the surf breaking over them, so I moved over onto the trail which cuts through the trees and plant growth.  Upon reaching the base of the rainforest cliffs, I passed by a trail entrance sign with an information board discussing current conditions.  This was the beginning of the Z-Trail.  The Z-Trail is widely known to be an extremely steep and challenging zigzag climb up a series of switchbacks which gain around 1,300 feet in elevation in less than one mile.  This is the hardest part of the hike, especially for those with heavy backpacks heading out on a multi-day trip.  The good thing, though, is that there are several spectacular viewpoints of Waipio Valley along the way, mainly at the far right sides when going up.  The views stretch back into Waipio Valley to lakes, rainforest cliffs, taro farms, the beach below, the Waipio Valley lookout and steep road down, and the waterfalls.  Along with Kaluahine Falls, two of the other main waterfalls which are visible include Hiilawe Falls and the smaller left side twin Hakalaoa Falls (which is often dry).  Hiilawe Falls has a titanic drop of 1,450 feet and is considered to be one of the most majestic falls anywhere on Hawaii.  During my hike, both Hiilawe Falls and Hakalaoa Falls were both fully visible with clear skies and flowing with a full water level.  After admiring the view for some time, I finished the climb up the Z-Trail and entered the rainforest portion of the hike.  The rainforest passes through 13 gulches with stream crossings.  During my hike, I noted that these included 4 larger gulches and 9 smaller gulches.  The rainforest is filled with all kinds of tropical trees and plants as you will see within my full set of photographs.  It is fairly easy to keep track of where you are when crossing through the rainforest gulches by looking at a topographical map and also monitoring the mileage as posted on the Emergency Helipad signs.  It was during my hike into the first larger gulch when I encountered the Queen's Bath.  The Queen's Bath is a beautiful and inviting pool of water below the prettiest waterfall that you directly pass along the Muliwai Trail.  It is a fitting name since Waipio Valley (also known as The Valley of the Kings) was the secret boyhood home of Hawaiian King Kamehamea I.  Beyond the Queen's Bath, the Muliwai Trail continues to wind through the rainforest gulches and across stream beds.  None of the stream crossings presented a challenge during my hike.  The rainforest crossing took me about 3 hours each way.  Upon arriving above Waimanu Valley at the first lookout point, I was truly awestruck.  I hadn't seen any hikers all day and now I was looking down into one of the most secluded, hard-to-reach, beautiful valleys on the Big Island.  The scene was incredible and equally as impressive as the views into Waipio Valley.  The highlights were the views of Waimanu's black sand beach far below and seeing Waiilikahi Falls across the valley.  When I reached the first lookout point, I sat down and had lunch, and then made the decision to go ahead and descend into Waimanu Valley.  I was doing good on time (about 5 hours from starting at the Waipio Valley lookout) and really wanted to see the beach and valley below.  The trail down was steep just like the road into and the Z-Trail out of Waipio Valley had been.  When I finally got down, it was time to cross Waimanu Stream.  Once again, it wasn't overly difficult.  Water got up to my waist but it felt good to cool off.  I then checked out the campsites and beach area and was quite impressed.  Waimanu Valley was extremely beautiful and it would have been a great place to spend several nights.  As it was, I had Waimanu Beach all to myself for an hour and that was quite special.  I enjoyed the peaceful tranquility and beauty of the waves crashing as I relaxed on the black sand with my hiking boots off.  At about 1pm, I had to begin the long hike back.  On the hike back, I passed 3 other backpacking groups and also took a refreshing dip in the Queen's Bath.  It felt great and was actually one of my day's highlights.  Upon reaching Waipio Valley and crossing back over Waipio Stream, it started getting dark outside.  So I finished my hike up the Waipio Valley Road much as it had started when going down earlier -- by flashlight.

I've seen this question posed on the internet -- which hike is better, the Kalalau Trail on Kauai or the Muliwai Trail on the Big Island?  Personally, I enjoyed this hike significantly more for several reasons.  First, the Muliwai Trail is a lot less treacherous and there aren't really any fully exposed cliff areas.  The Z-Trail does have a little bit of vertical exposure but there are generally small walls and brush growth along the edges to help keep hikers safe.  Second, I estimate that the Muliwai Trail is only 2/3 as difficult as the Kalalau Trail.  There is less cumulative elevation gain and the gulch crossings are a lot easier.  (If you are starting from the Waipio Valley lookout parking area as I did, I would say that the trail is 3/4 as difficult.)  Third, the scenery is superior at the beginning and end in the two major valleys.  Granted, the scenery along the middle of the trail is superior on the Kalalau Trail because there are better views of the coast.  Fourth, there are a lot less homeless encampments along the Muliwai Trail and in Waimanu Valley than are found at Kalalau Beach. The final stats of my hike of the Muliwai Trail were -- 365 photos (120 included in this report), 164 ounces of water (including 16 ounces filtered out of a stream), 19 miles, 13 hours 10 minutes (beginning at 6:20am and finishing at 7:30pm), and approximately 5,250 feet of total elevation gain (or 2,175 feet going to Waimanu Valley and 3,075 feet coming back which includes the additional climb up the road).  My hike took place on February 6, 2015.
This hike contains sections of exposed cliffs with steep vertical drops, dangers from ocean currents and waves breaking on the shore, dangers from stream crossings with potentially high water levels, risks of water contaminated with Leptospirosis, and challenges from heat, humidity, and muddy conditions.  All hikers should use extreme caution.
Many more photographs taken during our visit are available for viewing for this destination.  To see all of them, choose one of the two options presented below.  The two options are Slideshow viewing and Trip Report viewing.  The Slideshow option allows for viewing larger images with an autoplay option and a full screen option (available on most browsers).  This option works very well for large computer screens and tablets.  The Trip Report option allows for viewing smaller pictures in a standard scroll-down format and enlarging of any panoramic photos taken during our visit.  Click on the option of your choice to view all of our photos from this destination.  The Slideshow format opens in a new browser window and the Trip Report format uses the same browser window for viewing.