U.S. Navy Vice Adm. Matthew L. Nathan, center, the surgeon general of the Navy and chief of the Navy's Bureau of Medicine and Surgery, salutes sideboys as he leaves the hospital ship USNS Mercy (T-AH 19) in Pearl Harbor, Hawaii, June 29, 2014, during the Rim of the Pacific (RIMPAC) 2014 exercise. RIMPAC is a U.S. Pacific Fleet-hosted biennial multinational maritime exercise designed to foster and sustain international cooperation on the security of the worlds oceans.