The San Geronimo Valley runs west from Fairfax towards the coast, a narrow green valley of meadows, oaks and redwood groves, with small communities like Woodacre, Forest Knolls and Lagunitas strung along Sir Francis Drake Boulevard. It feels much further from San Francisco than it really is, and in the evening, when the fog creeps in from the ocean and the light goes soft and silver, it is magical.
Just west of Lagunitas, Samuel P. Taylor State Park protects a forest of coast redwoods along Lagunitas Creek, with tall, straight trunks rising into the mist and ferns covering the ground. The creek is one of the most important spawning streams in California for endangered coho salmon, and in winter, after heavy rains, you can sometimes see the fish fighting their way upstream. The park also has a history: Samuel Taylor built a paper mill here in the 1850s, the first on the Pacific coast, and later a resort.
On the question of swimming, the honest answer is that the creek is too precious and the reservoirs in the hills are off limits for swimming. The better place is a short ride west, at Tomales Bay, a long narrow inlet along the San Andreas Fault. At Tomales Bay State Park, near Inverness, small beaches like Heart's Desire face calm, shallow water that warms up in summer, sheltered from the ocean waves. The water is cool but pleasant on a hot day.
The riding here is a joy. Sir Francis Drake Boulevard twists through the valley and the redwoods with good curves and a decent surface, although it is narrow in places and busy with cyclists on weekends. Beyond, the roads to Point Reyes, with its lighthouse, cliffs and elk herds, and the coast road along Tomales Bay are among the best in the Bay Area. Watch for deer, especially at dusk, and for fog that can make the road slick.
Fairfax, about seventeen kilometres east, is the nearest town of any size, with fuel, cafés and a laid-back vibe; it is known as one of the birthplaces of the mountain bike. Lagunitas gave its name to a well-known craft brewery that started here in the 1990s before moving to Petaluma. Stop in the redwoods, breathe in the damp air and enjoy the silence.