U.S. Marines with Marine Corps Air Ground Combat Center (MCAGCC) swim through an amphibious obstacle course aboard MCAGCC, Twentynine Palms, Calif., Oct. 7, 2014. U.S. Marines, Dutch Marines, and Royal Marines were competing in the Combat Center's High Intensity Tactical Training Black Alligator Challenge. (Official U.S. Marine Corps photo by Staff Sgt. Leon M. Branchaud/Released)