City Beneath the Sea (1953)

"Fabulous Lost World -- at the Bottom of the Sea!"

Divers Brad and Tony arrive in Jamaica to attempt salvage of the Lady Luck, sunk with all hands and a million in gold. They charter the American Beauty, skippered by attractive Terry, but cannot find the ship. But there's more to the Lady Luck than meets the eye, and undersea skullduggery forms a counterpoint to Brad's romance with Terry, and Tony's with cabaret singer Venita.