A cottage and lighthouse were constructed on the The Isle of Mull for the production of this movie. The set building utilized the skills of a seventy-two year old master thatcher, a local of the island.
This movie is what led George Lucas to hire Richard Marquand to direct Star Wars: Episódio VI - O Retorno de Jedi (1983). Lucas was mainly impressed how Marquand was able to finish a difficult production on time and on budget, a factor which was critical on a huge production like Star Wars. Lucas also had to hire someone who was not a member of the Hollywood director's union as he was having a dispute with the Director's Guild at the time.
The film was made and released about three years after its source novel of the same name by author Ken Follett had been first published in 1978. The novel was Follett's first best-seller, with over three million copies sold prior to the production of this movie. The novel was first published in 1978 and the Mystery Writers of America awarded it the 1979 Edgar Award. The novel was originally entitled with the working title of "Storm Island", the setting of which represents the second half of both the novel and the film.
As of 2015, this is the only theatrical feature ever made from Ken Follett's work. All other Follett screen adaptations have been made for TV.
The U-53 is portrayed by a British S-class submarine.