Mara Maru (1952)

Greg Mason, salvage diver in the Philippines, finds his partner Andy drunk and raving about treasure. Whatever it is, somebody wants it badly enough to kill Andy and frame Mason for murder. Cleared by an insinuating private eye, Mason is immersed in intrigue, with detective Rainier, sinister Benedict, mysterious Ortega, and Andy's comely widow all somehow involved. Soon various parties, not really trusting each other, are on a sea voyage to dive for they know not what...