In San Francisco Take the Muni Metro T line (or specially marked Metro trains on game days) directly to the AT&T ballpark — the Second and King Muni Metro station is right next to the Harbor. Muni buses 15, 30, and 45 also stop within one block of the Harbor.
From the Peninsula and South Bay: San Mateo and Santa Clara Take Caltrain from stations throughout Santa Clara and San Mateo counties directly to the ballpark —the Fourth and King streets station is two blocks away from the Harbor. Or, take BART from Colma or Daly City, to downtown San Francisco. Then walk (it's about a mile down Second Street from the Montgomery Street station) or take Muni Metro to the Embarcadero & Townsend.
From the East Bay: Alameda and Contra Costa Take BART to the Embarcadero or Montgomery Street stations and walk or transfer to Muni Metro. The Alameda/Oakland Ferry Service provides direct service to the ballpark for most games and service to the Ferry Building at other times. AC Transit also provides bus service from many East Bay cities to the Transbay Terminal, a short walk to Embarcadero & Townsend.
From the North Bay: Marin and Sonoma Take Golden Gate Transit's Larkspur Ferry or Blue and Gold's Tiburon/Sausalito Ferry to the ballpark—direct service is available for most games. At other times, take regular ferries to the Ferry Building. Then walk or take Muni Metro to the Harbor.
From Napa and Solano Take the Vallejo Ferry to the Ferry Building and walk or take Muni Metro to the Harbor. You can also take Vallejo BARTLink to the El Cerrito del Norte BART station, ride BART to the Embarcadero or Montgomery Street stations and walk or take Muni Metro to the Harbor. From Vacaville or Fairfield, take Fairfield-Suisun Transit to the Pleasant Hill BART station and ride BART to the Embarcadero or Montgomery Street stations.