THE CRUCIBLE Marines endure the Crucible, a 54-hour training exercise, on Marine Corps Recruit Depot Parris Island, S.C. The exercise forces recruits to combine and employ everything they have learned during the previous three months. Recruits cannot become a U.S. Marine unless they complete the event. SHARE: Download: Full Size (0.05 MB) Credit: VIRIN: 892384-U-AJL46-136.jpg Photo Gallery