Konahuanui, also known as K2, is among the tallest mountains on O'ahu and the second tallest mountain in the Ko'olau Range with a summit elevation of 3,150 feet. There are many ways to access the summit approach trail, but by far the most scenic is via the Pu'u Ohia and Pauoa Flats trails, a 6-mile out-and-back trek through tropical alpine cloud forest.
Parking is located on Round Top/Tantalus Drive. Across the road from the parking lot is the trailhead for the Pu'u Ohia Trail, which starts immediately by gaining in elevation toward the summit of Mount Tantalus. The trail emerges onto a telephone/radio tower access road that is seemingly out of place among the dense bamboo forests. The trail then veers behind the radio towers and begins a slow descent through native plant restoration grounds to Pauoa Flats, a muddy, yet flat trail through tropical forest. Many other trails lead to Pauoa Flats, so be careful not to inadvertently wander off. Following Pauoa Flats will lead to the Nu'uanu Lookout with sweeping views of the Nu'uanu Reservoir, Pali Highway, and the windward side. Here there is a bench to sit and take in the views. The lookout marks the end of the maintained trail, with the summit trail starting beyond the bushes to the right of the lookout clearing. The trail from here is kept inconspicuous to deter amateur hikers; from here on the trail is considered strenuous and is not maintained.
The summit trail quickly ascends the ridge toward the peak of Konahuanui, forking quite early. The left trail follows the contours of the ridge and is more gradual, and the right trail follows the spine of the ridge with precipitous drops on either side. Both trails reconnect before the final ascent up the ridge. The route to the summit is frequently muddy and slick, making proper footing and good judgment key. There are ropes in many of the steep sections, although they can be significantly weathered and unreliable. At the summit of K2 there is a grassy clearing from which hikers can continue on to K1 (the tallest peak in the Ko'olau range) or back they way they came.
Check the weather conditions before attempting this hike. The summit is frequently in the clouds, and moisture makes the trail extremely muddy and slick. Be prepared for cloud forest mountain conditions as well as tropical heat.