Johnny and Theresa Gray (Richard Egan and Jane Russell) have been married a year and are broke. At Johnny's urging they go in with Johnny's friend Dominic (Gilbert Roland) to search for gold at the site of an old shipwreck.
They're joined by Gloria (Lori Nelson), who has a boat they can use, and a Jesuit priest, Father Cannon (Robert Keith), who is interested in recovering religious artifacts believed to have gone down with the ship.
Along the way they deal with dangers including sharks and a shark hunter (Joseph Calleia); the climax of the film occurs when Theresa becomes stuck in the wreckage with a shark circling nearby.
Other than that, it's a time-passer, but not much more than that. The plot meanders along without much conflict, and while the film has some very nice location footage, shot in Hawaii and Florida, a big drawback is that numerous scenes were obviously shot in a soundstage tank.
The aforementioned Egan and Russell make a cute married couple, although Russell has a baffling Hispanic accent which comes and goes. It wasn't necessary to the story so it's an odd choice, especially as it was difficult for her to remember to use it!
Lori Nelson is unfortunately wasted. The cast also includes Eugene Iglesias and Ric Roman.
UNDERWATER! was directed by John Sturges. It was filmed by Harry J. Wild in Technicolor Superscope, with underwater photography by Lamar Boren.
UNDERWATER! is an RKO film which is shown periodically on Turner Classic Movies. The trailer can be watched at the TCM website.
Be sure to check out a fantastic color shot of a NYC billboard for UNDERWATER! at Viewliner Ltd, and there's more on the film and Superscope at the Widescreen Museum.