Pleasanton Ridge is beloved and heavily used, but because there is only one main trailhead, at the southern edge of the park, the further you hike, the more solitude you'll find. On my first visit, I crossed paths with joggers, dogwalkers, and cyclists for the first 2 miles, but then encountered no one until I returned back to that 2-mile-from-the-trailhead zone. Up on the ridgeline, near 1500 feet, it was just me and and the wildflowers swaying in the wind.
     There are many loop options, but for a medium or long hike Ridgeline Trail plays the prominent role. Ridgeline accesses the far northern reaches of the park, Kilkare Canyon and Sinbad Creek. A round trip hike to the edge of the park is more than 14 miles, with some serious climbing on both legs of the journey. The shortest loop at the park combines Oak Tree and Woodland Trails, for a less than 2 mile stroll. Early spring is a great time to visit Pleasanton Ridge -- mid to late March is just about ideal for a loop on Thermalito and Ridgeline Trails. Unlike some East Bay parks that are grazed by cows, Pleasanton Ridge is quick to dry out after the winter rains end. You'll probably find smooth, dry trails and green hillsides even before the oaks have their fresh spring leaves. In summer it is often HOT, and there's very little shade on most trails.
     For the featured hike, start uphill on Oak Tree Trail. As the trail winds steeply up an exposed hillside, coast live oaks are the dominant tree, with poison oak, sticky monkeyflower, coyote brush, and snowberry in the understory. Interstate 680 is audible, but traffic noises decrease as you head up the broad multi-use trail. At 0.15 mile, Woodland Trail sets out from a signed junction at a curve in the trail. Turn left onto this path, open to hikers and equestrians only.
    Climbing uphill at a moderate grade, Woodland is dominated by coast live oaks. There's an astonishing amount of poison oak growing alongside the trail, so don't stray off course. In the first few weeks of spring, California buttercups add a dash of cheerful color. Later, in early May you might see Chinese houses. Switchbacks break up the climb (ignore any shortcuts). As the trees thin, the trail levels out and sweeps into a meadow. A look over your shoulder reveals the bare ridge on the east side of Interstate 680. At 0.6 mile, Woodland splits into two evenly worn trails. The trail to the left cuts through a meadow, while the trail to the right skirts the meadow. Stay to the right, as the park district is attempting to restore the meadow. As Woodland Trail continues an easy climb, it edges near Oak Tree Trail; a connector path veers right at 0.8 mile, but stay on Woodland. The trail ducks under some oaks and then ends at a junction with Oak Tree Trail at 1 mile. Continue straight through the cow gate to a large well-worn junction.
     From here trails wander hither and yon. Ridgeline Trail heads south (left). The chunky looking trail uphill to the right is a shortcut. Straight, and then to the left, Oak Tree Trail continues downhill along a corridor of poison oak and chaparral. Straight, and then rightish, is the trail you want, Ridgeline. (If you have a paper map this junction is marked as #5.) As Ridgeline Trail ascends slightly, curving to the right around a hilltop, in early spring you may see a few flowers in the grass, including blue-eyed grass and bluedicks. Ahead, the trail splits in a Y, just before a cluster of trees. This orchard, the first of several olive groves, was planted around 1900. The Thermal Fruit Company grew cherries, almonds, prunes, and apricots in the southern portion of the park until the early 1930's. None of those trees survive, or a record of who planted the olive trees, but the olive trees are sturdy, and many still bear fruit. At a signed junction at about 1.3 miles, bear left onto the spur trail to Olive Grove Trail.
     Sunol Ridge looms ahead, across Kilkare Canyon. The olive trees provide a perfect picnic spot, especially for a hiker pining for the Italian countryside. Just make sure the park's cows haven't relieved themselves nearby! At about 1.35 miles, Olive Grove Trail enters from the left at a signed junction. Continue straight, and again, straight when Olive Grove breaks off to the right at a signed junction at 1.45 miles. The broad path passes a pond, then joins with Thermalito Trail at a signed junction at about 1.6 miles. Stay to the left as a side trail breaks off on the right side. Thermalito edges alongside a small, but steep canyon. Buckeyes are mixed in with valley and coast live oaks. The trail crosses over the top of a creek, and a dry waterfall (at least in the spring) is overrun with poppies. On the left side of the trail, valley oaks hold court over a pretty meadow. On a March hike, the grass was filled with yellow johnny-jump-ups, a jovial blossom in the violet family. When I visited again, in early May 2002, squirrels scattered through the grass when a golden eagle soared overhead. Thermalito ambles uphill past a small pond, and passes another meadow speckled with flowers in spring. The first of the peaks on Ridgeline comes into view, on the right. At a signed junction at 2.3 miles, a spur trail climbs to meet Ridgeline. (This is an option, but the grade is steepest hiking north on Ridgeline; the easier choice is to continue on Thermalito and then hike south on Ridgeline.) Continue straight/left on Thermalito.
     There are many side trails and shortcuts in this part of the park, so try to stay on the main trail. Thermalito Trail begins a light climb as the path curves around the base of a hill. Look for a well-stocked woodpecker granary tree on the right side of the trail. At 2.7 miles, a spur trail to Ridgeline veers right at a signed junction. Turn right and head uphill.
    The grade is steep, but this section is short, and at 2.85 miles, the spur tapers out and ends at a signed junction with Ridgeline Trail. From here, you can turn right and descend back to the trailhead, but for the best views, turn left and ascend the first crest. It's a butt-crunching ascent on a multi-use trail (look out for bicycles) and when you get to the top you may be dismayed that the trail dips a bit and then climbs to another, taller peak, not visible from the previous junction. Keep climbing to a second crest. This is the turnaround point for the featured hike, at 3.05 miles. From here, at about 1530 feet, Mount Diablo looms across the populated valley, and the mountains of Sunol Regional Wilderness and Mission Peak rise up to the south. On this often windy hilltop the wildflowers grow close to the ground. Look for tiny blossoms of lupine, redmaids, shooting stars (an early flower past its prime in spring), johnny-jump-ups, and bluedicks. The trail continues north, bucking like a rodeo bull, cresting and falling along the ridgeline, and if you'd like to extend your hike 2 more miles, you can continue along Ridgeline for another mile to Sinbad Creek Trail and then turn around. Ridgeline ends a bit past that and any further hiking involves climbing down (and then back out) Kilkare Canyon.
     Retrace your steps back to the junction with the spur you climbed from Thermalito, then continue straight on Ridgeline Trail. After a short, bearable climb, it's all downhill from here. Ignore trails heading left at 3.6, 3.8, and 3.9 miles. Continue downhill on Ridgeline. The trail ambles along a barbed wire fence tangled with poison oak, California sagebrush, and sticky monkeyflower. Olive trees stand to the right and left. A picnic table and water fountain are welcome at a sunny spot on the side of the trail. You'll reach junction 5 again at 4.6 miles, where the two legs of Ridgeline meet. Turn left and retrace your steps back to the junction of Oak Tree and Woodland Trails. For a change of pace, descend, to the left, on Oak Tree Trail.
    Traffic noises become noticeable and then increasingly loud as you hike downhill. A few large imposing sycamore trees step aside to let you pass. At 5.2 miles, the dead-end Sycamore Grove Trail sets out on the left side of the trail. Continue straight on Oak Tree. You'll pass the previously encountered junction with Woodland Trail at 5.7 miles. Retrace your steps on Oak Tree Trail back to the trailhead.

Total distance: 5.8 miles
Last hiked: Wednesday, May 1, 2002