The South Bay region borders on San Diego Bay and the Pacific Ocean.

Nature preserves in the South Bay region include the San Bay region include the San Diego Bay National Wildlife Refuge and the Otay Mountain Wilderness.

The Naval Base San Diego is located in the South Bay. It is the second largest surface ship base of the United States Navy. It is a major employer with more than 24,000 military personnel and over 10,000 civilians.

Other regions of San Diego County include North County and East County.