Kawailoa Trail is a 8.7 mile lightly trafficked out and back trail located near Haleiwa, HI that offers scenic views and is rated as difficult. The trail is primarily used for hiking and is accessible year-round.
Kawailoa is a beast of a trail only because it's seldom hiked and very overgrown. The route I used precluded it from being hiked in both directions in one day and ended up being just over 18 miles.
The trail itself is very well constructed and if well cleared would be a very easy and beautiful walk to the junction with the Ko'oalu Summit Trail.
Access from the bottom of the trail is difficult to obtain and would require permission from the US Army and Waialua Sugar Company. Without permission you're looking at roughly 6 miles of trespassing just to get to the trail head on Pa'ala'a Uka Road.
The overgrowth not only slows forward progress to a snail's pace, it also masks the trail's route several times and in the middle and upper sections. Pig damage also makes finding the trail difficult several times. There are some ribbons but they aren't reliable indicators of the route either. Have a GPS track of the trail and a map or prepare to spend a lot of time searching for the trail.
The Kawailoa Trail measured out to 5.85 miles from Pa'ala'a Uka Road to the KST one way.