Bedrock mortars used by Native Americans for pounding acorns that were found in the area are reminders of Sunol's first inhabitants. For the past century, however, the land known today as Sunol Regional Wilderness was used almost exclusively as ranch land. Under the East Bay Regional Park District's multi-use land management policy, cattle continue to graze in the 6,859-acre wilderness. Today, camping, picnicking, hiking, back-packing and equestrian trail rides attract thousands of park visitors a year. Visitors should bring drinking water because there is no drinking water in the park.
Old Green Barn Visitor Center
Visit the Old Green Barn Visitor Center for information about Naturalist-led programs and the self guiding Indian Joe Nature Trail. A selection of replicate Indian artifacts, cultural and natural history books, nature study items, wildflower seed packet, trail permits and topographical maps and other items are for sale at the sales counter. The Old Green Barn Visitor Center is closed on Thanksgiving and Christmas Day.
Exploration will reveal sandstone outcrops with fossils deposited in what was once ancient seabed. Great boulders of greenstone, schist and metachert indicate a turbulent past. The massive basalt outcrop at Indian Joe Cave Rocks provides sport and challenge to rock climbers.
Alameda Creek, Alameda County's largest stream, harbors an inviting creekside community of alder, willow and sycamore. Coast live oaks abound along with valley and blue oak, elderberry, madrone and gray pine. Spring brings wildflowers, including California poppies, mustard, goldfields and lupines, which carpet vast areas in yellow, orange and blue. A wildflower identification kit may be checked out at the Visitor Center.
Ground squirrels, yellow-billed magpies and red-tailed hawks share this wilderness with raccoons, skunks and black-tailed deer. Mountain lions are uncommon, but are occasionally sighted. Birding is superb along Alameda Creek with acorn woodpecker, black phoebe, titmouse, turkey vulture, and golden eagle commonly sighted. As many as 20 to 40 bird species are often seen in a single morning.