Weighed down by heavy equipment, cadets must perform several tasks in a pool being churned by artificial wave makers amid simulated battlefield chaos. Artificial fog, rain, and deafening noise are pumped in, darkness is punctuated only by strobe lights. Since its inception, every graduating cadet has met and mastered the Survival Gate # 4 challenge. (U.S. Army photo by Sgt. 1st Class Christopher Fincham)