Discovery Bay is a census-designated place (CDP) in eastern Contra Costa County, California in the United States, about 60 miles (97 km) from San Francisco. It is located in the East Bay region of the San Francisco Bay Area. Discovery Bay was originally a waterfront community built on a network of man-made dikes, surrounded by fresh water, except for the southeast quadrant, which comprises the golf course of Discovery Bay Country Club. Some homes have private docks with access to the Sacramento–San Joaquin River Delta. Newer developments have been added on former agricultural land to the west of the initial town-site. Road access is via California State Route 4.