Staff Sgt. Clarence C. Elicio, squad leader for Company A, 1st Battalion, 294th Infantry Regiment, Guam Army National Guard, inspects a tunnel at Qala-I-Jangi, Balkh province, northern Afghanistan. (Eddie Siguenza/U.S. Army)

A diver with the 7th Engineer Dive Detachment, 130th Engineer Brigade, soaps up on his diver equipment to make sure there are no leaks before diving into the ocean on Oct. 1, 2013, during Deep Blue, an annual exercise designed to reinforce safety and tactical proficiency during dive operations at Joint Base Pearl Harbor-Hickam. (Gaelen Lowers/U.S. Army)