Of the four camping areas within Angel Island State Park, Ridge Camp offers the best views of San Francisco, Alcatraz, the Golden Gate Bridge, and the Bay Bridge. It is a one-of-a-kind getaway for an adventure that is at once outdoors and urban, isolated and nearby, exciting and chill. The Ridge Camp campsites do not crowd each other and thus feel quite private, giving a sense that you have found your own secret perch from which to observe the bustle of San Francisco in a peaceful, natural setting. It's the grown-up version of sneaking out and camping in the backyard: You can see the lights on in the house but the crickets are chirping just outside your nylon cocoon.
Angel Island also offers plenty of fun ways to fill your day. You can circumnavigate the island in a few hours of walking on the 8-mile Perimeter Road, hike up Mount Livermore (788 feet, the highest point on the island), visit defunct military and immigration facilities, or explore any of the island's 13 miles of trails before turning in for the night. Once back at camp you'll have access to water, a picnic table, a barbecue station, and a decent latrine. Dress warmly: Ridge Camp is completely exposed to the ocean westerlies that blow through the Golden Gate.
Angel Island is popular with Bay Area residents because of its easy access from San Francisco and Tiburon via a fast, easy ferry ride. Day use slips for private boats are available in Ayala Cove, but overnight moorings are allowed only on the mooring balls in the middle of the cove for a $30 fee. It is theoretically possible to tie up and get yourself ashore to camp, but the simplest plan is to use the convenient ferry. The Blue & Gold Ferry departs San Francisco from Pier 41 with daily service. (Note: a dedicated kayak camp, one of the three other camping areas besides Ridge Camp, is available on the western shore of the island.)