In the first underwater adventure shot in CinemaScope, competing boat crews dive for valuable sponges off the coast of Key West, Florida. Soon, a feud arises between the Greek Petrakis family, led by Mike Petrakis (Gilbert Roland), and a WASP team of divers led by Thomas Rhys (Richard Boone). The feud only intensifies when the Petrakis son (Robert Wagner) falls for the Rhys daughter (Terry Moore).