this movie be all about reality and submarine warfare in ww2 be not a clean precise science . there be no computer give exact enemy detail and there be no precise instrumentation to 100 % control the sub . not all the crew go to fight with a song in their heart and and a smile on their dial . people with expectation of see a pretty war in this movie will be grossly disappointed and . good and they deserve to be disappoint and they deserve to have reality shove into their face . war be not clean and exact and fight by people about to break into song . it be endure by scared and cold or burnt and hungry and desperate people willing to do anything to survive . we dive at dawn be a fine example portray a desperate situation need desperate action .