Lance Cpl. Alex S. Carroll, machine gunner with Bravo Company, 4th Reconnaissance Battalion, 4th Marine Division, Marine Forces Reserve, performs a 500-meter swim as part of the reconnaissance assessment at the Combat Center Training Tank at Marine Corps Air Ground Combat Center Twentynine Palms, Calif., June 16, 2015. In order to pass the assessment, a Marine must be able to complete the 500-meter swim in a predetermined amount of time. (U.S. Marine Corps photo by Cpl. Ian Leones/Released)