Petty Officer 2nd Class Ryan Rivera rappels down the face of Joint Base Lewis-McChord's rappel tower in one of the Army's Mangudai challenge, May 1, 2013. The Army invited members of the Coast Guard to participate in their Mangudai event that challenges senior enlisted personnel with different obstacles that can sometimes last up to 72 hours. (U.S. Coast Guard photo by Petty Officer 3rd Class Jordan Akiyama)