The 1944 Alfred Hitchcock film set entirely on a lifeboat in the Atlantic is Lifeboat.
The film begins after a freighter and a German U-boat destroy each other during the Second World War. Survivors from the ship gather in a small lifeboat, and a German submarine survivor is pulled aboard. The confined setting turns the boat into a miniature society where questions of leadership, cooperation, nationality, and wartime morality are constantly tested.
Tallulah Bankhead leads the cast as newspaper columnist Connie Porter, alongside William Bendix, Walter Slezak, Hume Cronyn, Canada Lee, and others. The screenplay was written by Jo Swerling from a story by John Steinbeck, giving the film a literary and political dimension beyond its survival-thriller framework.
Although the story remains aboard the boat, the production used studio tanks, multiple boats, miniatures, and limited background footage. Hitchcock’s famous cameo appears as a photograph in a newspaper advertisement, a practical solution because his character could not plausibly join the survivors. Lifeboat is sometimes confused with Hitchcock’s The 39 Steps or Saboteur, but neither is confined to a single maritime setting.