Corporal Lewis Jackson, a Marine Corps Instructor of Water Survival with 8th Communication Battalion, provides further instruction for his Marines during their annual swim qualification aboard Marine Corps Base Camp Lejeune, N.C., March 4, 2015. A swim qualification every two years is a requirement for all able-bodied Marines to ensure mission readiness and to uphold the basic level of Marine Corps standards. (Official Marine Corps photo by Cpl. Jorden M. Wells/Released)