Bay seniors unwilling to brave the hordes at Muir Woods are advised to drive an hour south of the City to the hundreds of uncrowded acres, including many old growth redwood groves, in Portola State Park. Located in the Santa Cruz Mountains just south of La Honda it is a web of six open space preserves with extensive mountain biking trails and campsites (best to reserve in advance). Even if you prefer to hike closer to the park headquarters you will still have access to cathedral-like stands of redwoods including one 35 feet in circumference and 305 feet high. Sadly, it’s another park that does not permit dogs. Seniors $9.