Take highway 280 or 35 to the Sneath Lane exit in San Bruno. Drive along Sneath Lane, past the San Francisco County Jail, park at the gate.

The willows along the right of the trail indicate the presence of a stream. Twinberry is a shrub that grows along the stream. Look for its flowers or fruits which are produced in pairs. Look for Douglas' iris in the marsh where the stream crosses under the trail to go to San Andreas Lake.

Yerba santa, used by pioneers as a cold remedy, is plentiful along this trail. It has long, sticky, willow­like leaves and purple funnel­like flowers. The older leaves are blackened by a fungus.

During wet seasons, horsetails are plentiful in the roadside ditch. Indians and early settlers took advantage of its abrasive silica ridges and used this plant as a scouring wand. Toyon or Christmas berry has leathery, dark green leaves with serrate edges. This shrub produces bunches of red berries in the fall.

Stands of Eucalyptus grow near the top of the trail. At the top, turn left (southeast) onto the unpaved trail to see the Portolá Discovery Site. The Sweeney Ridge Trail to the right, goes along the ridge approximately 1.3 miles to the junction with Skyline College and Mori Ridge Trail.

When you reach the Portolá Discovery Site you can do some exploring.