Attempt at a submarine thriller crumbled because of all the idiotic, unnecessary conflicts the screenwriter jammed into the story. It might have worked as a caper flick but now we'll never know.
Splitting the crew between Brits and Russians, who hate and distrust each other from day 1, made no sense. The sets and exteriors were fine, ditto the quality of the players. This was one which tripped all over its screenplay.