San Diego Bay is a natural harbor and deepwater port located in San Diego County, California near the U.S.–Mexico border. The bay, which is long and wide, is the third largest of the three large, protected natural bays on California's entire long coastline after San Francisco Bay and Humboldt Bay. The highly urbanized land adjacent to the bay includes the city of San Diego (eighth largest city in the United States) and four other cities, including National City, Chula Vista, Imperial Beach and Coronado.