what part of the bay area is san jose
San Francisco Bay Area The "East Bay" is the densest region of the Bay Area outside of San Francisco and includes cities and towns in Alameda and Contra Costa counties, centered around Oakland. As one of the larger subregions, the East Bay includes a variety of enclaves, including the suburban Tri-Valley area and the highly urban western part of the subregion that runs alongside the bay.[19] The "Peninsula" subregion includes the cities and towns on the San Francisco Peninsula, excluding the titular city of San Francisco. Its eastern half, which runs alongside the Bay, is highly populated while its less populated western coast traces the coastline of the Pacific Ocean and is known for its open space and hiking trails. Roughly coinciding with the borders of San Mateo county, it also includes the northwestern Santa Clara county cities of Palo Alto, Mountain View, and Los Altos.[20] The "South Bay" includes all of the rest of the cities in Santa Clara county, centered around San Jose, the largest city in Northern California[21]. It is roughly synonymous with Silicon Valley due to its high concentration of tech companies, although the industry also has a significant presence in the rest of the Bay Area.[22] The "North Bay" includes Marin, Sonoma, Napa, and Solano counties, and is the largest and least populated subregion. The western counties of Marin and Sonoma are encased by the Pacific Ocean on the west and the bay on the east, and are characterized by its mountainous and woody terrain. Sonoma and Napa counties are known internationally for their grape vineyards and wineries, and Solano county to the east, centered around Vallejo, is the fastest growing region in the Bay Area.[23]