San Diego Bay is a significant natural harbor and deepwater port located in San Diego County, California, near the U.S.-Mexico border. It stretches approximately 12 miles (19 km) long and varies from 1 to 3 miles (1.6 to 4.8 km) wide, making it the third largest of California's protected natural bays, following San Francisco Bay and Humboldt Bay.

San Diego County, located in Southern California, is renowned for its stunning coastline, diverse landscapes, and vibrant communities. As of the 2020 census, the population was 3,298,634, making it California's second-most populous county and the fifth-most populous in the United States. Its county seat is San Diego.