U.S. Marines assigned to Echo Company, 4th Reconnaissance Battalion, prepare to conduct a 2000 meter swim during an amphibious assault operation on the Potomac river at Marine Corps Base (MCB) Quantico, Va., July 21, 2014. The training exercise was part of a week-long jump, dive, breach and shooting package conducted around various ranges on MCB Quantico. (U.S. Marine Corps photo by Pfc. Elisha N. Peake/Released)