One of six underwater-themed sci-fiction monster movies released around 1989/90. Others include: The Abyss (1989), Leviathan (1989), DeepStar Six (1989), The Evil Below (1989), The Rift (1990), and Lords of the Deep (1989).
Deep Star Six (1989) was the first release of several underwater-monster-themed feature films released during 1989-90, including The Abyss (1989), Leviathan (1989), The Evil Below (1989), and Lords of the Deep (1989), and 'The Rift' (aka 'Endless Descent', 1990). With the exception of 'The Abyss', none of these films were box office hits.
The name of the wrecked Spanish galleon ship was 'The El Diablo'.
Filmed in 1987, but not released until 1989.