On the day of our hike, we were confronted by a woman who gave us a verbal shakedown regarding our presence on the windward backroad. Cool as the wind that whips over the Nu'uanu pali, we dropped the name of our land manager buddy; however, this did nothing to impress our questioner who demanded some sort of written permission form. Of course we had no such thing. What probably saved us from being turned back were a couple things: 1) We didn't pressure out; 2) We kept walking while being interogated; 3) The woman didn't call her husband, or the cops, or a gun.
Our persistence netted us access to a hike that few people have the opportunity to traverse. The trail took us on a series of switchbacks across the side of the steep flanks of the windward Koolau range. From Kamehameha Highway, one would never expect that a trail could be blazed up such a steep pali. But someone, perhaps an ancient Hawaiian ancestor, had the wherewithal to undertake such a fete.
The switchback route has some hairy segments. Part of the trail crosses some treacherously narrow dried-up waterfall sections with sheer drops of 1500 feet or so. A self- admitted fear-of-heights person, I ventured forward and ever upward only because of the goading of my friends. I'm certain I would have turned back if I were alone.
With the perils of the interogator and sheer waterfall sections behind us, we reached the main ridgeline which is roughly 2,300 feet above sea level. Castle, which was used extensively during the search for the lost BYU-Hawaii student/hiker, taps into the Koolau Summit trail system which can take one to an array of central Oahu starting points. Atop the ridge is a beautiful little brook with the requisite ice cold water we all know mountain streams possess.
Not seasoned hikers, we underestimated the amount of water we
needed. Consequently, our water bottles were nearly dry at that
point. With a seemingly pristine stream at our disposal, no
problem, right? I can remember a discussion that went something
Me: "The water's okay to drink, huh?" Bob: "Hmmm...dunno about that." Guy: "Nah, the water's fine. We're up so high up here that no impurities or other crap could've gotten it." Me: "Yeah, that makes sense. Bottom's up boys."
All in all, Castle is a superb hike. If you have a chance, try it. You won't be disappointed.