The 'Aiea Loop Trail is a popular hike just outside of Honolulu, known for its beautiful forest scenery and relatively low grade. The trailhead is located in the Keaīwa Heiau State Recreation Area, where parking, bathrooms, campsites, and picnic areas are available. The loop starts at the well-marked signs at the back of the park and continues for 4.8 miles along the ridges of the Halawa Valley. The hike is not strenuous but does involve steep switchbacks and a small stream crossing toward the end of the trail. The trail usually takes an average hiker around three hours to complete, with some time to take in the beautiful surroundings.
Start through the tangled roots of aromatic lemon eucalyptus trees past a lookout under the power lines with views of downtown and Pearl Harbor. The trail then makes its way through strawberry guava trees that form a tunnel on either side. These trees ripen in late summer. The trail forks once. Keep to the right to continue on the loop. Here, the secondary forest canopy is taller and ferns line the ridge. The trail can be muddy at times as it begins to follow the contours of the valley walls. As you gain elevation you will begin to see native ohi'a and koa trees and will eventually come across a lookout to Interstate H-3. At this point the trail turns and begins to head back along another ridge lined with paperbark trees and Norfolk pines, which are seemingly out of place in the tropical environment. In a gulch on the return leg, a wing section of a crashed bomber from 1944 can be seen. There is also a plaque at the trailhead honoring the men who died there. The final descent leads to a lush green valley floor, where a small stream crossing and steep switchback section back to the lower camping area concludes the loop.
Dogs must be on a leash throughout the entire hike, and remember to pack out whatever you bring in. Be sure to bring plenty of water and good shoes for this hike, as it can be muddy.