This is one of my favorite loops in Joseph D. Grant County Park in the hills east of San Jose.
It starts at Halls Valley Lake and climbs steeply into the nearby hills along the Yerba Buena Trail (with a highly recommended side trip to McCreery Lake). It turns at the Canada De Pala Trail and returns on the Halls Valley Trail.
Along the way you'll see sweeping vistas of the nearby Diablo Range along with the observatories atop Mount Hamilton, the highest peak in the South Bay. Wildlife sightings are common: hikers have spotted coyotes, turkeys, bobcats, feral pigs, tarantulas and even the occasional mountain lion.
In springtime, this is one of the best wildflower locales in the Bay Area. Summer's too hot but winter's great (if muddy) and fall is interesting when the tarantulas come out.
The park sits on lands once owned by a prominent ranching family (hence the informal title "Grant Ranch"). The hiking can be arduous -- many of the rails were built for people on horses rather than on foot -- but what you can see along the way makes it worth every arduous step.
Take a minute to read the wildlife warnings -- I've seen a rattlesnake and friends almost bumped into a mountain lion. These animals are very shy around humans and almost never cause any problems, but you need to know what to do just in case.
Wear sunscreen (there's almost no shade here). Take plenty of water and snacks to stay hydrated and energized. This hike can take it out of you.
Contact: (408) 274-6121
Hours: 8 a.m. to sunset
Fees: Free at Halls Valley Lake; $6 per vehicle inside the main section of the park.
Dogs: Allowed (leashed)
Driving directions: From Highway 101 or Highway 680, take the Alum Rock Avenue exit eastbound in San Jose. Turn right onto Mount Hamilton Road and drive eight miles to the park -- go past the first sign for the park and park in the lot of the left side of the road, next to the large lake.