Hiking the Piei Mauka trail on Oahu, Hawaii on May 27th, 2012. The Piei Mauka hike is an overgrown and little-used ridge route to a 1,740 ft. peak in Kahana Valley known as Pu'u Piei. The route consists of narrow ridge walking and steep climbs along loose dirt and crumbly rocks. Although short in mileage, completing Piei Mauka takes a good portion of the day, putting itself in the category of a "day hike." Because the route is rarely ever used, the ridge is choked with vegetation, making progress slow and challenging.