rating: **
What a complete letdown, and this coming from a viewer who loves movies about treasure hunters...
Unfortunately, the main character, played by a stiff Robert Ryan, is so uptight, not only does he NOT go along with more energetic and assertive partner Anthony Quinn, to find gold on a sunken ship in a literal CITY BENEATH THE SEA from a volcano explosion hundreds of years ago, but he moves in to snake the booty first, just to teach his partner a lesson. That lesson is also taught to the audience, who must weather this bland fine-feathered friend who's also an extremely weak central hero, keeping this movie from being edgy, or entertaining...
This is a b-movie, so the low budget is deliberate, and mostly works... including scenes of the boys trudging in heavy "Diver Dan" style underwater gear with matte painted backgrounds. The technicolor is great looking, and otherwise these are capable actors and actresses. But this oceanic thriller is devoid of thrills, and pretty much... sinks upon impact.