 Later, when the U-boat faces ominous waves from a violent storm, Altberg orders the sub to submerge.Afterward, it is unable to surface when its ballast tanks fail to repressurize, leaving it being pulled southward without resistance while slowly sinking deeper into the ocean; they never see the light of day again.With the U-boat's batteries running low, and their chance of rescue non-existent, the six remaining, delirious crewmen attempt a mutiny, successfully disabling the U-boat by destroying several key instruments and gauges, even as they rave on about the curse of the ivory talisman.