In the beginning of the movie, whilst Gail (Jacqueline Bisset) is diving, she reaches under a part of the shipwreck and gets her arm yanked by the giant green moray eel, which causes her to scream in pain. In real life, her stunt double, Jackie Kilbride, dislocated her shoulder doing this scene. A diver was told to pull the stick attached to her wrist from inside the wreck. When the stick appeared, he pulled with all of his might (as instructed). The scene was done in one take, with multiple cameras, as there was no chance (or need) for repeating it.
An American network broadcast version contained fifty-three minutes of extra footage that was not shown in the theatrical release. This version was broadcast over two nights, and has never been released on DVD.
The shipwreck featured in the movie was actually the R.M.S. Rhone, which sank in 1867 off the coast of Salt and Peter Islands in the British Virgin Islands with 125 of 135 of her crew losing their lives. The R.M.S. Rhone broke into two pieces during the sinking. This movie was filmed at the bow section of the ship, located about seventy-five feet underwater.
Louis Gossett Jr., Jacqueline Bisset, Nick Nolte, Robert Shaw, and director Peter Yates had to learn how to scuba dive for this movie.
This movie soundtrack was notable for being pressed onto a colorful bright see-through ocean-blue vinyl, so as to evoke this movie.
Peter Benchley: Uncredited, the author of the film's source novel as the First Mate of the "Goliath". The appearance was the second of three cameos in films of his novels, the others being in Jaws (1975) and Creature (1998).