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 takes a look at some of O'ahu's best novice, intermediate and advanced trails.

When the celly is going off every 10 minutes and the electronic day planner is blip-blip-blipping with reminders of where you need to be next, even the primordial call of the wild can get lost in the cacophony.

That's why every diehard hiker worth his or her day pack keeps a mental black book of trails that can be easily completed in the time it takes to knock off a doctor's appointment or doze through an afternoon meeting.

For many East O'ahu hikers, Wa'ahila Ridge fits the bill. While relatively short, it offers all of the requisite pleasures of a classic Hawai'i ridge hike as well as a substantial, if somewhat brief, workout.

And who doesn't value a trail that doesn't require a day to complete and full night from which to recover, yet still allows for a stirring immersion into nature?

And, just 15 minutes from Downtown (on a really good traffic day), Wa'ahila Ridge is as convenient for townies as it is satisfying for hikers of all levels.

The trail starts at Wa'ahila Ridge State Recreation Area, near the top of St. Louis Heights. The park is home to scores of wild chickens who descend en masse from the brush at the sound of food-bearing visitors.

A narrow, paved path leads to the trailhead, segueing smoothly to a long, gradual climb up a broad path of dirt and rock.

The trail follows a mostly straight line through a forest of Norfolk pines and soon after, long sections carpeted by the needles of ironwood trees.

After passing a water tank on the left, the trail continues its upward climb through a dense grove of strawberry guava trees.

Even with dozens of visitors passing through each day, the trees provide abundant — and tasty — fruit throughout the late summer months.

Of course, trailside snackers need to be mindful the often precipitous hillsides on which the trees grow. It is not unheard of for overeager fruit pickers to reach too far and plunge down the ravine through thick, lacerating brush.

The trail here is wide but veined with exposed, toe-catching roots.

While the trail is clearly defined throughout, there are at least two sections where the geography of the surroundings seem to entice hikers to ignore easier if less obvious paths.

The first appears before just before a short plateau. If you turn right, you'll descend sharply along the exposed ridgeline. Turn left, however, and you follow the trail down along a safer and less steep path.

Once you have gained the ridgeline, the trail opens briefly to expose great, unimpeded views of Palolo and Manoa valleys.

The trail remains level just long enough for hikers to notice and appreciate long, glowing fields of 'uluhe fern and small outcroppings of maile and 'ohi'a lehua. Kukui trees grow on the slopes just off the trail.

The path rises and falls along three relatively small knobs.

Ropes are available in some of the steeper areas, but are not necessary given the rocks and other natural handholds that dot the trail.

Novice hikers may be tempted to rush up the steeper sections, but it's worth remembering that on an out-and-back trail, every climb must eventually be descended and every descent must be climbed. Fatigued quads can make both difficult, even dangerous.

As you clear the last of these short hills, a pair of utility poles appears.

Eventually, the trail leads to a larger, rocky knob. And while it is tempting to follow the ridgeline straight over the mass of rock, a quick look to the right will reveal a more level path that winds around the knob and reconnects on other side.

A large, open grassy plateau follows. The lack of tree cover here may argue against an extended break on a hot, sunny day. However, the spot is ideal for 40 or so winks in early morning or late afternoon — schedule permitting, of course.

After the clearing, the trail narrows significantly as it rises and snakes toward the final junction. This turnaround point is clearly marked with signs indicating the end of the Wa'ahila Ridge Trail and the start of the Kolowalu Trail.

Intermediate hikers may opt for very steep descent down Kolowalu on the left. Another trail, to the right, continues along the ridge up to Mount Olympus but is off-limits to the public (it passes a restricted watershed area).

Wa'ahila Ridge is generally rated as a novice hike because it is relatively short, easily navigable, and does not require advanced hiking skill. However, the numerous climbs and descents do require a decent level of physical fitness to safely complete.