Density Test Navy Seaman Lucas Jackson tests the density of metal pylons on a pier during exercise Valiant Shield 2016 in Kwajalein, Marshall Islands, Sept. 16, 2016. Jackson is a construction mechanic constructionman assigned to Underwater Construction Team 2. Navy photo by Petty Officer 2nd Class Daniel Rolston SHARE: Download: Full Size (2.35 MB) Tags: Sailors, training, Navy Credit: Petty Officer 2nd Class Daniel Rolston VIRIN: 160916-N-CN059-0100A.JPG Photo Gallery