U.S. Marine Corps Staff Sgt. Raymond J. McKim, an ordinance chief with Marine Tactical Electronic Warfare Squadron 2, holds his breath underwater during a Water Survival Advanced Course held aboard Marine Corps Air Station Cherry Point, N.C., Aug. 4, 2014. Students were tested on their ability to rescue distressed Marines in the water simulating real life scenarios. (U.S. Marine Corps photo by Lance Cpl. Jodson B. Graves/Released)