Cpl. Tanner Seitz, Marine Aviation Logistics Squadron 41, performs a rifle swim as part of aquatic conditioning during the Marine Corps Instructor of Water Survival Course at Marine Corps Base Camp Johnson, N.C., March 6, 2013. Seitz, from Keller, Texas, is one of more than 20 students attending the three-week MCIWS course. The course creates instructors who can train Marines to react and survive life-threatening situations in the water. (U.S. Marine Corps photo by Staff Sgt. Mark Fayloga)

More images of the Marines undertaking the Instructor Water Survival Course below - Click on a thumbnail in Gallery to see larger image