Mount Ka'ala is the highest point on the Hawaiian island of O'ahu and boasts some of Hawaii's most challenging yet accessible hiking. This rugged climb ascends a ridgeline from the western side with a total elevation gain of 3,500 feet in an 8-mile out-and-back trail. Do not underestimate this hike. From the baking heat to the misty cloud-shrouded summit, Ka'ala is demanding in more than one aspect, but the views (if you are lucky enough to see them on a clear day) and adventure can be well-worth it.
The trail starts in the hot, dry valley on the leeward side of O'ahu, with the first mile ascending an access road. On sunny days, this sweaty start can be brutal, since there is very little shade. At the end of the road, a dirt path continues relentlessly upward, passing a covered picnic shelter to the left, and onward into a stand of dense strawberry guava trees. A short descent to a stream bed provides only minimal relief before the trail continues upward to the left. As the ridgeline gets closer, the incline increases to nearly vertical with old ropes to be used as an aid.
The top of the prominent ridgeline is Kamaile'unu Ridge, where a fence and an unmarked junction make a perfect resting place after the grueling incline. The difficulty is far from over, though. Continue up to the right, making your way along the fence and the narrow ridge. This is perhaps the most difficult section of the trail. Here a series of large boulders requires some steep scrambling with cables for security. This notorious section requires careful footing and can be risky in wet conditions or when attempted by inexperienced hikers. Remember that even if conditions are optimal on the ascent, they may change and make the descent much more hazardous. After the last boulder, a short yet continually steep section brings you to the signed entrance of the Mount Ka'ala Natural Area Reserve, where a half-mile plateau and misty alpine bog are an unusual sight so close to the summit of the tallest mountain.
The Natural Reserve was established in 1981 and covers over 1,100 acres around the summit plateau of Mount Ka'ala, protecting delicate native flora and fauna. There is a slender boardwalk that makes traversing the bog easy and interesting. Take some time to appreciate the unique habitat here! At the end of the boardwalk is a clearing with a plaque and bench as well as a Federal Aviation Administration radar station, marking the somewhat anticlimactic summit.
For better views on clear days, traverse the FAA radar complex fence along the outside perimeter. Security is high at this radar station; abide by marked signage. At the far end are astounding views of downtown Honolulu and Diamond Head in the distance. Continuing counter-clockwise around the perimeter are views of central O'ahu, pineapple fields, and the northern coast. Return to the plaque and make a careful descent the same way you came up (descending via the auto road is strictly prohibited).
Make sure to carry enough water, as the trail is heavily inclined the entire way (minus the final bog traverse), and pack out whatever you bring in. The trailhead is remote; do not leave any valuables in your car. Plan for this hike to take most of the day, starting early for the best chance of having clear views from the summit. Enjoy what is arguably one of the most rewarding, rugged, yet accessible hiking trails on the entire island!