Johnny Gray, his wife Teresa, his friend Dominic Quesada and Dominic's girlfriend Gloria (who just happens to own a boat) are on a diving expedition off the coast of Cuba, searching for sunken treasure. (Teresa is supposed to be Cuban, and some of her dialogue is in Spanish, but Jane Russell does not attempt a foreign accent in her English-language dialogue). In particular, they have dreams of finding a 17th century ship containing a life size solid gold Madonna with precious jewels. They realise, however, that even after they have found the wreck, they will have to face many perils before they can recover the treasure. They also discover that they face competition from a group of local shark fisherman who are suspicious about their activities and who refuse to be fobbed off with their story that they are merely geologists collecting samples.
The film was directed by John Sturges, a director whose work could vary in quality but who at his best was responsible for some of the great classics of the fifties and sixties such as "Bad Day at Black Rock", "Gunfight at the OK Corral" and "The Great Escape". "Underwater!" is not really in the same class as any of those great films. One of its main weaknesses is the casting of Richard Egan, a rather stiff actor more notable for his impressive physique than for his acting talents, in the leading role of Johnny. As Johnny is a complex character, not a mere action hero, the film would have been better with a stronger actor in this part. The rest of the cast are rather better, although I suspect that a lot of the film's appeal, at least for male viewers, was the chance to see Jane Russell showing off her own equally impressive physique in a swimsuit.
Overall, however, "Underwater!" holds up pretty well today. On one level it is an exciting adventure story, in which the treasure-hunters have to battle sharks, moray eels and other underwater dangers. (In this respect it is far superior to something like "The Deep" which attempted to tell a roughly similar story some two decades later). A film shot underwater must have been something new and original in 1955; these scenes were not actually shot under the sea but in a specially constructed tank. On another level, however, it is a parable along the lines of "Treasure of the Sierra Madre" about what gold can do to men's souls, although it does not have quite the dramatic power of John Huston's masterpiece and lacks its tragic ending. Johnny becomes obsessed with the quest for the statue to such an extent that he is quite prepared to sacrifice his own life, or the lives of his companions, to find it. In the conflict with the fishermen it is Johnny who is the aggressor. It is notable that the cast includes a Catholic priest who acts as a sort of moral compass for the rest. These two layers of meaning help to keep the film watchable nearly sixty years after it was made. A bonus is the attractive musical score based around the popular hit tune "Cherry Pink and Apple Blossom White". 6/10