A California State Park, Angel Island is the largest of San Francisco Bay’s three islets (the others are Alcatraz and Yerba Buena). The island has been, at various times, a prison, a quarantine station for immigrants, a missile base, and even a favorite site for duels. Nowadays, most visitors are content with picnicking on the large green lawn that fronts the docking area; loaded with the appropriate recreational supplies, they claim a barbecue pit, plop their fannies down on the lush green grass, and while away an afternoon free of phones, televisions, and traffic. Hiking, mountain biking, and guided tram tours are other popular activities here.

Feeling adventurous, then take the Ferries of the Blue & Gold Fleet (415/705-5555; www.blueandgoldfleet.com) from Pier 41 (Fisherman’s Wharf) travel to Angel Island. Boats run on a seasonal schedule; phone or look online for departure information. Or, catch the Tiburon-Angel Island Ferry (415/435-2131; www.angelislandferry.com) to Angel Island from the dock at Tiburon Boulevard and Main Street. Boats run on a seasonal schedule, but usually depart hourly from 10am to 5pm on weekends, with a more limited schedule on weekdays. If you have to have your car with you, take U.S. 101 to the Tiburon/Highway 131 exit, and then follow Tiburon Boulevard all the way downtown, a 40-minute drive from San Francisco.

Passengers disembark from the ferry at Ayala Cove, a small marina abutting a huge lawn area equipped with tables, benches, barbecue pits, and restrooms. During the summer season, there’s also a small store, a gift shop, the Cove Cafe (with surprisingly good grub), and an overpriced mountain-bike rental shop at Ayala Cove.

Angel Island’s 12 miles of hiking and bike trails include the Perimeter Road, a paved path that circles the island. It winds past disused troop barracks, former gun emplacements, and other military buildings; several turnoffs lead to the top of Mount Livermore, 776 feet above the bay. Sometimes referred to as the “Ellis Island of the West,” Angel Island was used as a holding area for detained Chinese immigrants awaiting admission papers from 1910 to 1940. You can still see faded Chinese characters on some of the walls of the barracks where the immigrants were held.

The 1-hour audio-enhanced open-air Tram Tour of the island costs $14 for adults, $13 for seniors, $9.50 for children 6 to 12, and is free for children 5 and under; schedules vary depending on the time of year. Your best bet is to check in at the Cove Cafe upon arrival on the island for the current day’s tram schedule.

Guided Segway tours of the island are available as well March through November. The 2 1/2-hour interpretive tour circles the island’s paved Perimeter Trail and cost $65 (there’s a shorter $35 afternoon tour as well). All riders must be 16 years and older. (415/435-3392 or visit www.angelisland.com.)

You can also tour around the island, thanks to guided sea-kayak tours. The 2 1/2-hour trips combine the thrill of paddling stable, two- or three-person kayaks in an informative, naturalist-led tour around the island (conditions permitting). All equipment is provided, kids are welcome, and no experience is necessary. (415/488-1000; www.seatrekkayak.com). Note: Tours depart from Sausalito, not Angel Island.