Jack Hawkins wrote in his 1973 autobiography "Anything for a Quiet Life" regarding this film, "All of us in the film were sure that we were making something quite unusual, and a long way removed from the Errol Flynn-taking-Burma-single-handed syndrome. This was the period of some very indifferent American war movies, whereas 'The Cruel Sea' contained no false heroics. That is why we all felt that we were making a genuine example of the way in which a group of men went to war."
The most successful film at the UK box office in 1953, as well as a surprise hit in the US.
Donald Sinden had lessons to make him talk in a higher-pitched manner, as the producers felt his real voice was too deep for the young character he played.
If you look carefully, you will see that the rank insignia on Ericson's (Jack Hawkins') sleeves are in a different "font" from those of the other officers on his ship. This is because Ericson is RNR (Royal Navy Reserve: former naval personnel retained as reservists or - and indeed the novel makes it clear that Ericson had served at Jutland before joining the Merchant Navy), whilst the other officers are RNVR (Royal Navy Volunteer Reserve - men who joined after the outbreak of the war or civilians with no prior sea experience).
Donald Sinden was originally supposed to play First Lieutenant James Bennett, until Stanley Baker was cast instead. Therefore, Sinden ended up playing the much larger role of Sub-Lieutenant (later Lieutenant-Commander) Keith Lockhart.