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. This summer, Advertiser reporter Michael Tsai takes a look at some of O'ahu's best novice, intermediate and advanced trails.

Of the myriad feelings that Mount Olomana have been known to evoke — fear, awe, excitement — ambiguity has never been one of them.

While Diamond Head might cut the most recognizable figure in the O'ahu skyline, it is Olomana, with its three distinct towering peaks, that has captured the imaginations of generations of local hikers.

Some see the out-and-back trail that links its trio of peaks as a stout but worthwhile challenge that rewards skilled, careful hikers with spectacular views and thrilling climbs and descents. Others, particularly those familiar with its long history of calamity, regard it as a lure to recklessness and personal jeopardy.

With its steep ascents, narrow, rocky pathways, and windswept ridge line, the complete 5-mile, out-and-back trail offers as many perils as any day hike on the island.

Still, the initial section leading to the first peak can be safely completed by intermediate hikers who are in good shape and who can safely climb a 15-foot rock face with the assistance of a rope.

The second and third peaks should be attempted only by expert hikers in strong physical condition.

The hike starts beneath a thick canopy of trees along a short zig-zag of switchbacks before steadily ascending past short, rocky climbs and even shorter flat, grassy respites. After a short but slippery climb up a red-dirt hill, the trail resumes through long corridors of dense forest. (In the mid- to late-summer, cherry guavas are ripe and abundant all along the lower sections of the trail, allowing for quick, energizing breaks all along the initial climb.)

Shortly before the first peak stands a 15-foot rock face, a wise turnaround point for beginning hikers. A climbing rope is anchored near the top for support, but, as with any rope, hikers are advised to test it carefully before using.

The trail ascends sharply until it reaches the first peak. The broad, stable ridge top is an ideal place to stop for a quick lunch. And, with a 360-degree view of Maunawili Valley, the Ko'olaus and the Windward Coast, it's also the best spot on the trail for photographs.

Depending on one's disposition, the looming presence of the spire-like third peak, seemingly so close, can be irresistibly attractive or final confirmation that some challenges are best left unexplored.

To many experienced local hikers, the hike to Olomana's second and third peaks marks a sort of graduation from one level of hiking ability and experience to the next. And it's a crossing that must be earned.

The second summit, like the middle portion of any trilogy, is often underestimated by those looking ahead to the conclusion. Yet, while the approach to the second peak looks relatively easy from the vantage point of the first peak, hikers realize all too quickly that the middle jewel of this jagged crown is hardly a middling challenge.

The descent off the peak is very steep and unstable and the saddle is flat but narrow, about half a shoulder length in some areas, with sheer drops on either side.

The ridge line then climbs sporadically around large clusters of rocks and boulders to the peak.

Having achieved two of the three peaks, it can be difficult for hikers to turn back without making it to the third. However, the return leg from the third peak back to the first (not to mention back to the trailhead) is more physically taxing than the approach, and hikers should exercise good judgment in evaluating their level of fatigue.

The descent to the saddle is steep and crumbly and hikers need to be comfortable lowering themselves down a series of ropes, sometimes across long stretches where the footholds are unreliable or nonexistent.

As the ridge narrows, hikers should carefully evaluate the available pathways that connect to the peak. Climbing directly over rock formations leaves one vulnerable to sudden wind gusts; often there are narrow paths around the sides that have already been roped.

The summit itself is unspectacular, but its achievement is something worth savoring with a deep chug of Gatorade.

Just remember that, for all of the effort it took to make it to the summit, there's still the return trip.

Reach Michael Tsai at mtsai@honoluluadvertiser.com.