9000 acres of bone dry wilderness, mostly vertical and so scarcely used that you can go off trail without adverse impact.
Bicycle friendly. Helmets are required.
There is a small campground with water, toilets, and hot showers. No reservations. The campground is open full time from April through October, and sporadically in March and November.
Follow Mt. Hamilton Road eastward (head for the observatory) out of San Jose - it passes through the park.
USGS 7.5' Topo Maps