Ahuimanu Uka: Summiting the Obscure Windward Ridge to Aiea Ridge

June 7, 2010 • By Peter Clines

Since I had to work on Saturday for National Trails Day, I figured I would make up for it on Sunday by adding a fourth option to the ʻAiea trail network: a windward continuation.

After months of putting it off, yesterday became the day for a summit attempt of this obscure windward ridge. I had been looking for a new route on that side and spotted a ridge that begins behind ʻĀhuimanu and climbs to a peak north/west of the ʻAiea Ridge terminus. This ridge is fairly prominent, situated between Ulupaina Uka to the south (see pic below) and Kalahaku Teeth to the north.

Scouting & Route History

My initial scouting trip began from a poor access point, but subsequent clearing trips started from the end of Heno Place (~300 ft elevation). The trail starts wide and well-ribboned, likely sharing access with the Club's ʻĀhuimanu waterfall route.

After several hours of initial exploration, I found that the subtler ridge just south (left) of the prominent one was the ideal path:

• lower Swath: An existing swath led up a broad ʻuluhe slope close to the trailhead.
• Steep & Notch-Free: Unlike its neighboring prominent ridge, this route had no major notches, offering a consistent uphill climb but good views north toward Kualoa (see pic below)
• Brittle Rock Climb: Around 800–900 ft elevation, the ridge narrowed significantly into steep, brittle rock requiring heavy upper-body work using scattered "trumpet" trees as handholds.  

The Summit Climb: Scree, Exposure & Fog

Loaded with over 200 feet of rope, I hit the trailhead just before 9:00 AM. By 9:45 AM, I reached my prior trouble spot at 900 ft. Clinging to available roots and finessing rotten rock, I clawed my way through several tricky, vertical pitches.

Above 1,000 ft, the ridge briefly resembled the narrow dikes on the cemetery route to Manamana. Past 1,400 ft, heavy cloud cover rolled in, replacing exposure with extremely dense vegetation. Pushing through thick blackberry thorns and a wall of ʻuluhe, I finally hit the junction with the main prominent ridge.

Nearing the summit, I encountered the intimidating "Sheer" wall feature. Clinging to clumps of grass on a near-vertical face, I hauled myself over the top and reached the summit at 1:55 PM (2,450 ft elevation).

Traversing to the ʻAiea Ridge Terminus

Drenched in cold rain and surrounded by thick fog, I navigated south along the Koʻolau Summit Trail (KST). Using a watch altimeter, compass, and wind orientation, I navigated past two false spurs and a powerline tower, topping out at the the summit of the Aiea Ridge Trail (2,700 ft) at 3:00 PM.

At 4:00 PM, I reunited with August, Nate, and Nikolaj, who were finishing their Halawa-to-ʻAiea traverse. We hiked out together down the main trail, reaching the ʻAiea State Park parking lot at 7:00 PM.

Route Summary & Trail Details

• Location: ʻĀhuimanu (Windward Oʻahu) to Aiea Ridge Trail
• Trailhead: End of Heno Place, ʻĀhuimanu
• Key Landmarks: Kalahaku Teeth, Ulupaina Uka, KST Summit, Powerline Towers
• Terrain: Extremely steep, crumbling rock, narrow exposed dikes, dense ʻuluhe, and thorny brush

-Pete