I've probably hiked into the valley a half dozen times or more since the trail is located near to Leeward Community College in Pearl City where I work. On days when I've been pressed for time or didn't feel like driving to a more remote location to get some exercise, I motored to the top of Waimano Home Road for a workout on this trail.
The trailhead for Waimano Valley is the same one for Waimano Ridge. Park in the dirt lot just to the left of the entrance gate to Waimano Home. At that point is a hunters' check-in kiosk where you can list your name and other information if you want (I usually don't sign but find it interesting to scan the list to see who did).
Follow the trail on the valley side (left) of the fence and in less than 100 yards you'll reach a junction where you should head left and down into the valley on wide path that probably once was a jeep road.
Soon you'll find yourself in a serene, wide Waimano Valley. High above to the left is the ridge where Pacific Palisades sits. While descending, you'll see some homes atop the ridge and occasionally you'll hear a dog yelping from high above. Most of all, notice the green beauty and the soothing swoosh of the wind through the treetops. Ahh, lucky we live Hawaii.
In minutes, the descent into the valley will end and you'll be striding along the usually quietly flowing Waimano Stream. Trees shield the trail from the sun for most of the route along the stream which would bring welcome shade on steamy summer days. A few shallow pools are available for splashing about if you so choose. It's also possible to explore areas along the stream if you feel like tramping about.
After strolling along the stream for about a half mile, you'll arrive at junction marked by a good-sized mango tree. There, the trail heads right, up and out of the valley. In some places you'll find yourself huffing and puffing straight up the slope; at others you'll have a chance to return to more normal breathing patterns when the trail switches back and contours across the face of the mountainside. No danger at all here.
Ten minutes or so of ascending will bring you to a sign-marked junction with the upper Waimano Trail. If you feel energetic and have some time, turn left and follow the contour trail as far into Waimano Valley as you like, even to the Koolau Summit some six miles distant. Usually, I'll head mauka 15 to 20 minutes to a rocky outcropping with a nice view of the upper valley. If I have time, I'll continue even further to the point where the trail reaches another junction with Waimano Stream (from the trailhead to this upper junction takes about 45 minutes to an hour).
If time and/or energy are in short supply, turn right at the signed junction and head back on the upper Waimano trail which will take you back to the trailhead.
All in all, a great little hike is Waimano Valley. Check 'em out if you're in the Pearl City area.
----- Trail update: In March '97, the trail has been cleared beautifully by what I'm guessing is a state maintenance crew. The path has been weedwacked ten feet wide so that a truck could traverse it (if it were possible for a truck to get to the trail). What's more, the upper Waimano Trail all the way to the summit was worked on by the Hawaiian Trail and Mountain Club clearing gang in late-February '97.