North of Waimea on Kauai, the Kohua Ridge Trail is a 2.5 mile trail open to hiking. It provides a dramatic view of Waimea Canyon from the eastern side, which most people never see.
Access to the actual trailhead can be difficult -- it is off a very rough 4WD road. Many users park early on the road and continue several miles on the 4WD road to the trailhead.
To reach the trailhead from Waimea, head north on SR550 (Waimea Canyon Drive or aka Kokee Road) for 15.7 miles (to between milepost 15 and 16). Turn right on Mohihi-Camp 10 Road heading east for 1.6 miles. At this point, only continue if you have a 4WD vehicle. The actual trail starts at the 5.2 mile point on this rolling road through the forest. The trailhead sign can be easily missed, so watch your mileage. Head south on the trail for 2.5 miles to the overlook.
Here are some notes on adventuring in Hawaii. First, unlike mainland forests, the tropical island forests can grow very dense and can mask dropoffs. Plus, the trails can be very wet and slick most of the year (December to February is the main rainy season, but expect rain all year round). Stay on the trail to avoid disorientation. Second, speaking of disorientation, be aware that most Hawaiian topographic maps use the Old Hawaiian Datum. When trying to use the latitude/longitude from those maps with a GPS unit, you will think you are 0.4 miles south/southeast of where you really are. Kind of important in a dense jungle. Third, the bacteria Leptospirosis is found in the local waters and mud. It causes flu like symptoms within 2-20 days of contact, and can be fatal if not treated with antibiotics. Fourth, when hiking about, walking sticks can be very helpful for stablity in the slick conditions, for probing mud hole depths and clearing webs of the tiny crab spider.
Overall, Kohua Ridge Trail is the 20th most popular hiking trail of all 45 hikes in Hawaii.