This hike is a major adventure! It is both physically difficult and technically challenging. Bring plenty of water and snacks; there is no water along the route. The reward for your hard work comes, though, in lush springs, hidden lakes, woodlands, beautiful meadows, tunnels of manzanita, and unique rocky terrain. Mt.Tamalpais is amazing for many reasons, but its habitat diversity separates it from hiking anywhere else in the Bay Area.
The hike starts at the parking lot for Lake Lagunitas. There are water and restrooms at the trailhead. Head into the picnic area and up along the spillway to the dam. Head right at the top to circle the lake counter-clockwise. Go across the first bridge. Just after the second bridge, Colier Springs Trail is on the right (Junction #1). Be ready, this is a steep climb. It is both physically difficult and technically challenging. Colier Springs is the steepest trail on the mountain (and is seldom used). After this climb of 1,300 feet in less than a mile, most of the day's climbing will be out of the way. As you near the top, the water from the spring is flowing again and the trail levels off.
Colier Springs (Junction #2) is a lush little spring. A grove of redwoods, with giant chain ferns and vanilla grass, flourishes here. Several trails intersect at this point, so be sure to read the sign posts and take Upper Northside Trail towards Rifle Camp and Potrero Meadow. Upper Northside Trail contours along through a mixed forest of tall trees and deep shade. After you pass International Trail, coming in from your left, you break out of the forest at a serpentine ridge. The flora here is different due to the lack of soil, hotter temperatures, and low moisture. The junipers and manzanita here are stunted and deformed looking due to the lack of water and nutrients.
Rifle Camp (Junction #3) with picnic tables, BBQ grills, and a pit toilet seem a bit out of place after three miles of hiking. I'm still not sure why they have BBQ grills here. You would need to pack in the briquettes for miles just to use them! Head up the fire road for a few 100 feet until you reach the edge of Potrero Meadow. Catch the trail on the right that cuts across the meadow. The big oak on the right side of the trail is a good place for a spot of rest. The trail follows the drainage from the meadow over to Potrero Camp (Junction #4). This is a beautiful spot with year-round water. California newts and even pollywogs (in spring) can be found in the pools.
Kent Trail is on the right before a small bridge into Potrero Camp. It starts with a quick climb up more serpentine rock into chaparral. From here the trail descends through very rocky terrain, so take care. There are at least three official trails that cross the trail on your way down. Most are signed, but stay on Kent Trail. Kent Trail passes through some of our favorite places on the mountain. There are large stands of manzanita that grow over the trail, creating a tunnel of black and red gnarled branches. Chinquapin, which grows to a medium sized tree, is evident in all the spiny seed shells on the ground. Like a welcome breeze, the heat fades quickly as you near Swede George Creek, which flows year-round here. Flowering current, giant chain fern, and other water-loving shade plants grow along the banks.
Important: junction #5 at 4.7 miles into the hike. This is a key junction in the hike. If you make a wrong turn here you end up on the backside of Alpine Lake, which will add miles to your hike. The junction occurs after a quick descent into a deeply shaded forest in small flattish depression. Go right onto the signed Stocking Trail. There are a couple other trails coming into this junction, so take a second look. You will know you are on the correct path, because just over the rise (100 yards) is Hidden Lake. It is more like a swamp in the fall. Succession is marching forward quickly here. The sedges and rushes fill most of the lake and the rest is covered with fallen trees. Just past the lake is the spring that feeds it. A stand of large redwoods and an amazing patch of giant chain ferns covers the spring water coming out of the ground. This time of year, the spores on the backside of the leaves are red and look like links in a chain, giving the fern its name. Native peoples would collect the spores and use them as red paint for baskets.
The next section of trail goes through unique terrain. Most of the trails on Mt. Tamalpais or the surrounding area are either contour trails with down slopes on the side, like Upper Northside Trail, or they are old fall-line trails (logging skid roads) that go straight up and down, like Colier Trail. This area, though, is full of hummocks or mounds of dirt. It looks like the English moor with mixed forest on it. The trail winds its way in between, up, around and over them. Some of the depressions fill with water in the winter, forming vernal pools.
By now we were getting tired. Stocking Trail comes out onto Rocky Ridge fire road. We went right, up the fire road for about half a mile until it dead-ends at Lagunitas Rock Springs fire road (Junction #6). Once there, turn left and head down for 3/4 mile until you reach signed Lower Berry Trail, which is on a flat section of the fire road on your left side. When you reach Bon Tempe Lake, go right. You will be resting your feet in just 15 minutes.
Getting there: From Hwy 101 go west on Sir Francis Drake Boulevard for 5.2 miles to Fairfax. At the stoplight, go left on Claus Drive, quick left on Broadway Avenue, quick right on Bolinas Road. Go 1.5 miles and take a left on Sky Oaks Road. Go up to the lakes entrance (fee required) and then all the way to the Lake Lagunitas parking lot.
For more information, see the book Hiking Marin by Don and Kay Martin at Marin Trails.