Acclimation Period Before Marine Corps Boot Camp Could Stave Off 'Recruit Crud' Marine Corps recruits make phone calls to inform their next of kin that they have arrived safely at Marine Corps Recruit Depot Parris Island, South Carolina, June 25, 2020. The recruits are now ready to begin training after spending two weeks in quarantine as a protective measure against COVID-19. (Daniel Johnson/U.S. Marine Corps) 15 May 2021 MCRD San Diego -- On a recent American Airlines flight from Dallas-Fort Worth to San Diego, the pilot took to the public address system to salute the dozens of young recruits onboard for starting their rigorous journey to become U.S. Marines "as soon as tonight."