Marine Corps Recruit Depot San Diego is a United States Marine Corps military installation in San Diego, California. It lies between San Diego Bay and Interstate 5, adjacent to San Diego International Airport and the former Naval Training Center San Diego. MCRD San Diego's main mission is the initial training of enlisted male and female recruits living west of the Mississippi River. Over 21,000 recruits are trained each year. As of 2022, 1.5 million recruits have completed their boot camp training at the Depot. The Depot also is the home to the Marine Corps' Recruiter School and Drill Instructors School.

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 12 miles (19 km) long and 1 to 3 miles wide, is the third largest of the three large, protected natural bays on California's 840 miles (1,350 km) of coastline, after San Francisco Bay and Humboldt Bay. The highly urbanized land adjacent to the bay includes the city of San Diego and four other cities: National City, Chula Vista, Imperial Beach and Coronado.