U.S. Navy crew members on board the hospital ship USNS Mercy conduct a mass casualty drill during Pacific Partnership 2015 in the Philippine Sea, July 16, 2015. U.S. Navy crew members on board the hospital ship USNS Mercy conduct a mass casualty drill during Pacific Partnership 2015 in the Philippine Sea, July 16, 2015. SHARE: Download: Full Size (0.414101 MB) Tags: Photo Essays Credit: VIRIN: 982194-V-LTV93-011.jpg Photo Gallery