 Based on Marshall Pugh's book "Commander Crabb", it was made following the publicity created by Crabb's mysterious disappearance and likely death during a Cold War incident a year earlier.It was the first Universal Pictures film in SuperScope

The film depicts events in Gibraltar harbour during the World War II, Italian frogman and manned torpedo attacks, although the film's depiction of those events is highly fictionalised.For example Crabb spent several months deactivating mines brought ashore by other divers before learning to dive himself.