From summit ridges to lush, green valleys, fast-running streams to bone-dry brush, Hawai'i's public access trails offer an unrivaled variety of unique hiking experiences — sometimes on a single trail. Advertiser reporter Michael Tsai has taken a look at some of O'ahu's best novice, intermediate and advanced trails.

One of the island's most unique hikes, Kealia Trail and Access Road is also one of the most overlooked and unappreciated.

Sure, it's something of an acquired taste, but while its profile may not sound particularly attractive — a seemingly endless series of switchbacks at the start; steep climbs up a broad dirt trail; and close proximity to a popular hunting area — it does offer a great, elevated perspective of the activity around the bordering glider port, a safe but worthy challenge for trailrunners and other fitness buffs, and stunning views of Makua Valley and the Wai'anae Mountain range for hikers who don't mind also glancing at wire fences, shot-riddled hunting signs and an occasional water tank.

The trail starts behind the airfield, along a wide, mostly level gravel pathway to the left of a concrete structure and just past a scattering of old airplanes and airplane parts.

A series of 16 switchbacks gradually elevates you along the towering cliff facing the airfield. As you wend your way along the contours of the mountain, you can see fixed-wing gliders taking off and landing, even gliding parallel to your line of vision with the North Shore coastline in the background.

Each switchback is relatively long, but not very steep, and getting to the top is simply a matter of patience. Along the way, take note of the abundant wiliwili, with their thick, gnarled trunks and orange flowers, as well as several tall kukui trees.

The switchbacks end at a small grove of ironwoods and you'll pick up the trail across a small gully, eventually ascending up a wide dirt path lined with silk oaks and Christmas berry.

From there the trail rises and falls several times along the ridgeline as you pass a water tower to your left and a gate and fence to your right.

At around 1,600 feet, the trail ascends steeply through a forest of Cook pine and eucalyptus before opening up to a great view of the North Shore.

The road splits at several junctions, but continue along the straightest, most obvious path.

Along the way, you'll pass the Kuaokala Public Hunting Area. If you miss the sign, just look for the bullet holes in the various natural and man-made structures in the area.

After a steep descent and subsequent climb, you'll come to a junction. To the right is a road leading to the Kaena Point Satellite Tracking Station; take the path to the left along the Mokule'ia firebreak road heading toward Makua Valley. You'll eventually come to a four-way junction and continue straight ahead while the firebreak road splits to the left.

At another junction, follow the path to the right, which will take you up Kuaokala Trail to the summit, where you can enjoy a terrific view of Makua Valley, 'Ohikilolo Ridge and the Wai'anae mountain range.

The trail is hot and dusty in the dry summer months, but very slippery in rainier weather. While certain sections are eroded or deeply rutted, the trail does not require any technical skill. Its beginner-intermediate rating is based on the quad-taxing climbs and a few narrow sections along the switchbacks but well-conditioned hikers should have no problem. And while the road walking may seem a bit boring to hikers who prefer rock-hopping and root-skipping, the trail's broad, accessible pathways make a great hill workout for trailrunners.