I don't remember them using suicidal tactics in the movie and I've seen it several times now,, but of course you are getting a highly edited, out of context, trailer version on YouTube. There were a couple of situations in the movie where the sub was damaged and rose to the surface. What I do remember was the sub commander howling over the radio and taunting the convoy screen, which the film company admitted wasn't historical but was a plot device used to humanize the enemy.
Bob