Peninsula (Bay Area)
The Peninsula region of the San Francisco Bay Area lies immediately south of the City and County of San Francisco -- reaching from its famous neighbor to the north into the high-tech region of Silicon Valley. San Mateo County is the main county in the Pennisula region. While many of the Peninsula's residents work and play to the north or south, the Peninsula has its attractions, including some beautiful wilderness areas.
Though the Peninsula technically extends from the Pacific Ocean to the San Francisco Bay, in practical use, it more commonly refers to the Bay side of the area. It contains few major cities or ports and the Santa Cruz mountains divide the region in half north-south, with a large wilderness area that's great for hiking and mountain biking.
The Bay Area has three major commercial airports:
All three airports are served by public transportation. The regional metro-rail service BART runs directly to SFO and connects to the commuter rail line Caltrain, as does the San Mateo County bus service SamTrans. The East Bay bus service AC Transit and a connecting bus to BART, AirBART, run to OAK. Santa Clara County's Valley Transportation Authority runs a bus (Line 10) connecting SJC with Caltrain and that county's light rail and bus system.
Motorists can reach the Peninsula from OAK by crossing the bay on the Bay Bridge (Interstate 80, to the north), the San Mateo-Hayward Bridge (Highway 92, to the south), or the Dumbarton Bridge (Highway 84, farther to the south). From SJC, drivers can take Highway 87 to US-101 northward, although avoiding 101's rush-hour traffic is often recommended. (For longer trips northward, try the scenic, parallel Interstate 280.)
Getting to the peninsula by car is easy, provided you can avoid the traffic. Be aware that reaching the peninsula via a bridge will incur a toll charge. These toll charges can be tricky to estimate, even for locals, so consider using this handy reference to know how much to pay and when: (Bay Area Tolls ).
This commuter railroad runs up and down the peninsula between San Francisco and San Jose, stopping at most major towns and serving the San Jose International Airport (via a short transit bus at Santa Clara station). Some trains continue further south to Gilroy. It runs 7 days a week until about 1am (10pm on Sundays). If you've missed the last Caltrain, local bus service is available all night.
BART serves a small portion of the peninsula, with some trains terminating at either San Francisco Airport or Millbrae. Caltrain and BART connect at Millbrae.
The San Mateo County Transit District runs extensive bus service throughout San Mateo county, plus overlaps in Palo Alto and San Francisco. Some bus routes run all night. Normal bus fare is $2.00, express buses are $5.00, and Clipper cards are accepted. Useful bus routes include:
The San Jose VTA runs buses throughout Santa Clara County, starting in Palo Alto. Normal bus fare is $2.00, express is $4.00, and Clipper is accepted. Routes that serve the Peninsula include:
The two main highways running down the peninsula are 101 and 280. If you are driving from San Francisco to Palo Alto or San Jose, take I-280. It is a beautiful drive, free of advertising, well above the wilderness area. If you must drive on 101, avoid rush hour - it will be slow in both directions. The drive along the coast on State Route 1 (the Cabrillo Highway) is a beautiful, yet slow drive.
Many streets throughout the Peninsula have designated bike lanes, helping make cycling on the peninsula safer and easier. Key north-south bike routes include Alameda de las Pulgas, Middlefield Avenue, and Cañada Road.
Hiking in the Peninsula
About 30% of the Peninsula is nature preserve, parkland, or otherwise undeveloped. There are many opportunities for hiking and mountain biking, all a short drive away. The transition from the crowded town along the eastern coast to empty wilderness is a rapid one! Most parks are managed by the Mid-Peninsula Open Space District, while some are part of local towns or counties. Almost every park permits mountain biking, and most allow horseback riding.
Some excellent destinations for hiking include:
Be careful to check for ticks  after hiking in fields in the bay area. There is a high rate of lyme disease transmission in the Bay Area. If a bulls' eye rash develops at the tick bite site, immediately seek medical help and treatment with antibiotics.