Best Hikes on Oahu: The Waimano Ridge Trail

Basic Information

• Name: Waimano Ridge Trail
• Where: Pearl City, Hawaii
• Distance: 15 miles
• Max Elevation: 2,194 feet
• Elevation Gain: 2,773 feet
• Time: 8-10 hours
• Difficulty: Hard
• More Information: The Hikers Guide to O’ahu

Topographic Map of the Waimano Ridge Trail

Google Earth Map of the Waimano Ridge Trail

Elevation Map of the Waimano Ridge Trail

Directions

From Honolulu take the H-1 freeway west and then take Exit 10 that leads to Pearl City and Waimalu.  After exiting the highway take a right on to Moanalua Road that goes to Pearl City.  At the third traffic light take another right on to Waimano Home Road.  Follow this road all the way until it ends at a security gate for the old Waimano Training School and Hospital.

Parking

Hikers are not allowed passed the security gate.  All hikers need to park in the dirt area along the side of the road to the left of the security gate.  There is more parking across the road from the Pearl City Cultural Center:

There is not a lot of room to park and this place can get packed on the weekends.  However, since I arrived at the trailhead at 6:00 in the morning there was no one else there yet:

Hawaiian Meaning

According to the book, “Place Names of Hawaii” the word “Waimano” translates in English to “place of many waters”.  The various valleys that cut through this area each have streams flowing through them which makes it easy to understand where this name came from.

Narrative

The Waimano Ridge Trail is one of the longest hikes on Oahu and one I have been meaning to set enough time aside to do.  On a recent weekend I finally had the time as well as good weather to complete this hike.  The hike follows a 15-mile trail up the Waimano Ridge above Pearl City to the summit ridge of the Ko’olau Range.  The trailhead for the Waimano Ridge Trail begins just to the left of the security station.  It is well marked and impossible to miss:

Besides being a trailhead for the Waimano Ridge Trail it is also the trailhead for hikes to visit the Waimano Falls.  Before heading out on the trail hikers are asked to sign in on a roster located in a green mailbox.  When people complete their hike they are then asked to sign out on the same sheet of paper in the green mailbox:

After signing in I walked short distance down the trail until I came to a fork.  Going left leads to Waimano Falls while going right leads to the Waimano Ridge Trail:

The upper trail follows the security fence for a short distance:

The trail then leads away from the fence and into the forest:

The trail then comes to a bench that has a beautiful view of central Oahu:

At this bench a choice is made to either descend into the Waimano Valley or stay on the ridge longer before dropping into the valley later.  Since this is a very long hike I decided to stay on the ridge longer to make better time.  To stay on the ridge I followed the service trail that led back to the fence line:

As I followed the fence line I was impressed with how big the old Waimano Training School and Hospital is.  The facility was first built in 1919 and is 265 acres in size.  This large facility was originally used to house people with developmental disabilities.  It was closed in 1999 due to reports of poor building conditions and mistreatment of patients.  Today some of the buildings in the facility have been remodeled and are used to house various state offices:

At the end of the fence line trail there is a paved road that leads to a security gate:

From the security gate I followed the road that leads higher up Waimano Ridge:

Since I was hiking on a road I was making good time compared to hiking in the valley trail down below.  I soon game to a large water tank:

At the water tank the paved road turned into a dirt road:

From the dirt road I had nice views looking down into the Waimano Valley:

I also had views all the way down to Pearl Harbor located at the base of the Ko’olau Range:

The road passed the water tank I would soon find out was constructed to access the many power lines that were installed on this ridge:

The power lines provided openings in the forest canopy that gave nice views of the surrounding mountain ridges:

Eventually the dirt road turns into a trail that is marked with orange ribbons to help hikers stay on the correct path:

I followed this trail until it intersected with the connector trail that leads down to the lower Waimano Ridge Trail.  The connector trail is located at what appeared to be a camp site with some stumps:

To the left of the camp site I could see the Na Ala Hele trail sign that marked the connector trail:

Using the connector trail switchbacked down the side of the ridgeline towards the lower Waimano Ridge Trail:

As I followed the trail down the ridgeline I once again had some nice views of the surrounding mountains:

The connector trail is overgrown in some areas, but easy to follow.  It is also marked with pink ribbons which makes it very hard to get lost on this trail:

The connector trail intersects with the lower Waimano Ridge Trail at the point that it crosses over one of the branches of the Waimano Stream system:

It had not rained much in recent days which meant the stream was running very low, thus making it easy to cross:

Shortly after crossing the stream I came to one of the tunnels in Waimano Valley that were built by western immigrants to Hawaii to irrigate sugar cane fields at the base of the mountains:

At this point hikers can either hike through the tunnel or use a bypass trail:

I decided to bypass the tunnel because of how tall I am.  Crouching over all that distance was sure to leave me with a sore back.  So I turned around and used the bypass trail:

The bypass trail led to the top of an adjacent ridgeline that had a nice picnic shelter on it:

The picnic shelter was created by the Boy Scout troop from Kamehameha District Post 540:

The picnic shelter is located approximately 4-miles from the trailhead and is about the halfway point to the end of the trail on the summit ridge of the Ko’olau Range.  From the picnic shelter I had a nice view Ko’olau Range:

I also had a good view of the ridgeline across the valley from the picnic table to the northwest:

I spent about 15 minutes at the picnic shelter drinking water and eating a few snacks to power myself up for the remainder of the hike.  Once I was ready I followed the trail down into another valley:

As the trail descends it becomes very narrow with steep drop offs.  There are sketchy ropes and cables in place for people to hold on to if needed:

It is imperative to be very careful on this section because any fall off of the trail would likely be fatal:

At the bottom of the valley I came to a section of the Waimano Stream system that had three creeks flowing into one.  I noticed some stoneworks here that was probably part of the larger irrigation infrastructure that once existed in this valley:

At the stream crossing it is important to spot the pink ribbon that marks the trail that is located to the left of the middle stream:

From the stream the trail then begins another ascent up a ridgeline:

On this section of the trail I began to see a lot of native Hawaiian plants such as the koa trees:

Koa trees are what native Hawaiians used to construct canoes long ago.  Today koa wood is highly sought after for use in making furniture.  From this section of the trail I also had views towards the summit ridge of the Ko’olau Range.  The view was making me concerned that I would end up walking 15-miles and have no views due to the building clouds:

Here is a view from the ridgeline looking back down the valley towards the stream crossing:

On top of the ridgeline I walked by a large clearing that I thought may have been cleared for a campsite or helipad:

Passed the clearing the trail next came to a section of the ridgeline that featured a number of broken koa trees that I thought maybe a major wind storm destroyed:

This ridgeline was also the only section of the trail that I spotted lehua blossoms that grow on native ohia trees:

The ohia tree has an interesting legend associated with it due to its bright red blossoms.  The legend states that if you pick the tree’s lehua flower it will rain on the same day.  This belief goes back to a legend involving Hawaii’s goddess of fire Pele.  She wanted a great warrior named Ohia to marry her.  He refused because he was already in love with a woman named Lehua.  Pele was angry and turned Ohia into a twisted tree now called a ohia tree.  Other Hawaiian Gods took pity on Lehua for losing her lover and thus turned her into the Lehua flower so she could forever be with Ohia.  So if you pick the Lehua Flower you are separating Lehua from her lover which will cause it to rain due to Lehua’s tears.  I hoped no one picked any lehua blossoms on this day because I really wanted some good views once I reached the end of the trail.

As I looked towards the summit ridge I could see it was not completely clouded in yet:

Besides the very few lehua blossoms I saw, the only other colorful flower I spotted were these purple flowers spread out randomly in different sections of the trail:

From the broken koa tree area there is about two miles of hiking left to reach the summit.  This final two miles I found to be the toughest of the hike.  This is because the trail stays on a steady ascent as it switchbacks its way up the mountain and is where over half of the elevation gain for this hike occurs.  The below Google Earth image gives an indication of how the trail slowly ascends up to the summit ridge of the Ko’olau Range:

What made this section really challenging though is how the trail became overgrown with vegetation:

The higher up on the ridge that I went the worse the trail became due to the thick vegetation:

I was probably tripped over vegetation at least a dozen times.  I was definitely glad I wore pants for this hike because my legs would have looked much worse than they currently do.  Even with pants on, I still received scrapes, cuts, and bruises from the thick vegetation.  I also hit my head a number of times fighting through tree branches.  I was pretty frustrated and miserable on this part of the trail.  Fortunately the trail did have some good views to moderate my frustration with:

As I hiked higher up the ridge I could even see parts of Pearl Harbor in the distance:

As I continued my ascent, I thought the trail would eventually go directly up the ridge to the summit in front me like most Ko’olau Ridge hikes do:

However, I would soon discover that the trail does not directly ascend up the ridge and instead meanders its way to the right below the summit ridge.  It was a bit frustrating to see the Ko’olau summit right above me but the trail was not heading towards it:

The next picture shows how the trail meanders below the Ko’olau summit ridgeline:

This makes the hike feel much longer because the summit was right above me, but I had a whole lot of trail left before getting to the end.  In the below picture the gap between the mountains in the center-left distance is where the trail ends.  Notice on the bottom left that the trail is barely visible because of the overgrowth of plants:

Besides the threat of tripping on the overgrowth of plants, another danger was stepping into large holes eroded into the trail that cannot be seen due to the thick vegetation.  I actually stepped into one of these holes and fortunately my other foot was firmly planted and I did not fall in.  In the below picture you can kind of see one of these holes underneath the vegetation:

This next image shows the gap in the mountains that the trail very slowly ascends towards:

As I neared the gap in the mountains I could see a prominent peak along the Ko’olau Range in the distance:

The Waimano Ridge Trail ends at the gap where there is a large grass clearing that provided me a place to sit down, rest, and take in the views:

Here is a picture of the sign in the grass clearing that officially marks the end of the Waimano Ridge Trail:

Here is a closer look at the prominent peak located towards the south of the grass clearing:

The clearing that I was sitting on was bracketed on the south by this rounded peak:

I thought about hiking up there, but I was already tired of breaking brush to get to the grass clearing and thus decided to just enjoy the views from where I was at.  To the north of the grass clearing was another rounded peak marked with a large landslide:

Besides the surrounding mountains, from the grass clearing I also enjoyed a stunning view of the Waihe’e Valley down below me:

The Waihe’e Valley is located on Oahu’s Windward Coast and is a location I have hiked into multiple times before to check out one of the most beautiful waterfalls on the island, Hamama Falls:

Best Hikes On Oahu: The Hamama Falls Trail

I laid down on my stomach and looked over the edge of the cliff hoping to spot Hamama Falls.  The drop off is pretty steep, but not as bad as on other sections of the Ko’olau Range:

As I looked down into the valley I could not spot Hamama Falls because the foliage was too thick to see the trail leading to the falls:

Based on my prior GPS track, I estimate that Hamama Falls is located approximately in the area circled below:

After checking out the valley down I then proceeded to check out the ocean views:

The most notable ocean feature I could see was the Kaneohe Sand Bar which is a popular submerged island that many boats and kayaks frequent during the day when the tide is out.  When the tide comes back in the sand bar disappears:

I could also see Marine Corps Base Hawaii which is located on the Mokapu Peninsula that forms the eastern portion of Kaneohe Bay:

Below the Marine Corps base and in the middle of Kaneohe Bay I could also see Coconut Island which was once filmed as part of the classic TV show Gilligan’s Island and today is an ocean research center:

Way out in the distance I could see the islet of Mokoli’i which is more popularly known as Chinaman’s Hat:

A paddle out to Mokoli’i is one of my favorite kayak trips on Oahu:

Kayak Routes on Oahu: Chinaman’s Hat (Mokoli’i Islet)

After spending about 30-minutes on the summit I turned around and began my long descent back down the trail:

On my way back I had plenty of long distance views of the Pearl Harbor region.  For example here is a zoomed in look and Pearl Harbor from near the summit:

This next picture shows Ford Island located in the middle of Pearl Harbor:

This next picture shows Hickam Field that shares runways with the Honolulu International Airport:

Besides views of Pearl Harbor I also had views of central Oahu.  Most notably I could see the highest  mountain on Oahu the 4,025 foot Mt. Ka’ala:

Mt. Ka’ala is one of my favorite hikes on all Oahu:

Best Hikes on Oahu: The Mt. Ka’ala Trail (Waianae-Kaala)

Here is a view of the long ridge and valley walk that I had ahead of me:

Looking behind back towards the Ko’olau Range summit ridge it appeared the weather was actually getting clearer which meant warmer temperatures for the rest of my hike:

Before descending back down into the valley I could see the ridgeline ahead of me where the connector trail leads to the dirt road back to the trailhead:

My descent back down into the valley was quick a quick one:

I next began my ascent back up to the picnic table on the narrow cliff trail:

I eventually could just barely see the Boy Scout picnic table on top of the ridge ahead of me:

The picnic table was a welcome sight when I reached it because I could sit down and get out of the sun for a little while since the temperatures were now very hot:

I spent about 15 minutes here again drinking water, eating snacks, and enjoying the view looking back towards the summit of the Ko’olau Range:

From the picnic table I descended off of this ridgeline to cross another stream.  When crossing the stream I noticed another irrigation tunnel:

From the bottom of the valley I came to the connector trail and began to ascend up to the dirt road.  As I ascended the ridgeline I had a good view of the route I took to reach the end of the Waimano Ridge Trail at the small gap in the mountains pictured in the center of the below photo:

Here is a view of the Ko’olau Range from when I reached the top of the ridgeline:

Here is the view from the ridgeline looking towards the Waianae Range in western Oahu:

From the trail I was able to spot the Schofield Barracks military base in Central Oahu:

After taking in my final views I then walked back into the camp site:

Below is a picture of the trail sign located at the campsite:

From the campsite I followed the trail and dirt road back to the hospital.  Along the way I was able to admire a number of large power lines:

The breaks in the foliage provided by the powerlines gave me more views of the Pearl Harbor area:

As I walked down the dirt road I also noticed how eroded over the decades the road has become:

I soon found myself back at the water tank:

From the water tank I followed the paved road back to the old hospital complex:

I then followed the fence line back to the trailhead:

Conclusion

In total in took me 8 hours and 5 minutes to complete this hike with 5 hours needed to reach the summit and then 3 hours to get back down the trail.  I could have done this hike even quicker if the trail was in better shape in the later portions of the hike.  The condition of the last 2-miles of the trail as well as the long 15-mile distance is why I don’t recommend this trail to average hikers.  Better views on shorter, well maintained trails can be found throughout the Ko’olau Range.  I would only recommend this trail to advanced hikers looking for a challenging trail to complete.  With that said hiking to the picnic table and exploring the irrigation tunnels is a shorter and more interesting hike that I think average hikers would enjoy.  That hike can also be combined with visiting the Waimano Falls as well which is family friendly 2-mile hike for those with young kids.

Disclaimer:  On-Walkabout is a website about outdoor activities that is not affiliated with any state or national government.  The articles on this website are for informational purposes only and to inspire others to get outside.  The activity descriptions are given to showcase the beauty and fun of experiencing the outdoors.  The writer of On-Walkabout is not responsible for any accidents, injuries, rescues, legal issues, or loss of life by anyone attempting the activities listed on this website.  Outdoor activities can be dangerous which is why it is the responsibility of the reader to use common sense and understand their own abilities before attempting an outdoor activity inspired by this website.  Most importantly parents need to understand the ability of their children before attempting an outdoor activity.  Just because my young children completed a hike mentioned on this site does not mean your children can as well.  Be safe and I hope this website inspires others to go and enjoy the outdoors as much as I do.  

YOU CAN FIND MORE GREAT HIKES AT THE OAHU REGIONAL TRAIL FINDER:

Note: Further information about hiking on Oahu can be found in the below book: