Flora

Ranunculus californicus, in Sunol Regional Wilderness.

Common trees in the park include Coast live oak (Quercus agrifolia), Valley oak (Quercus lobata), Blue oak (Quercus douglasii), Mexican elderberry (Sambucus cerulea), Pacific Madrone (Arbutus menziesii) and Gray pine (Pinus sabiniana). Along Alameda Creek, riparian trees include White alder (Alnus rhombifolia), willow species, and California sycamore (Platanus racemosa).

In spring, wildflowers are abundant, including Chinese Houses, Ranunculus, monkeyflowers, California Poppy, goldfields, and several species of Lupines.

Fauna

California slender salamander

There are many bird species, including one of the largest breeding populations of golden eagles, supported by large numbers of a common prey and keystone species, the California ground squirrel. skunks and black-tailed deer are also common. Coyotes and mountain lions visit the park, though they are unlikely to be seen by visitors. A well-equipped Visitors' Center has a complete list of plants and birds to be seen in the park. Common amphibians and reptiles include the California red-legged frog, Pacific tree frog, California newt, Diablo Range garter snake, Western rattlesnake and San Francisco alligator lizard.

Ohlone Wilderness trail

The Ohlone Wilderness trail, a long distance footpath linking several East Bay regional parks, passes through the Sunol Regional Wilderness. It runs from Mission Peak Regional Preserve near Fremont to the Del Valle Regional Park near Livermore. Several backpack campgrounds exist along the way.

Much of the routes land is owned by the San Francisco Water Department. Right to pass is subject to a permit, which is available at the Sunol Wilderness entrance gate.

The terrain between Sunol Wilderness and Del Valle Park can be challenging. Rose Peak is the high point, only a bit lower than Mount Diablo in elevation.