Ocean Noir: 16 Fathoms Deep (1948)

Experience the romance and shadowy danger of sponge diving, film noir style! Lloyd Bridges carries the picture with hard-boiled narration throughout: "Below, you moved in shadows that have been there since the world began. In those shadows, things were living and growing and fighting. A world of beauty and danger.... And your only weapon was a four-pronged sponge hook and the brains of a man."