River Monsters (2009)

S09E01 Killers From the Abyss

Title: Predators of the Deep Plot: Wade embarks on the most challenging investigation of his life as he seeks to uncover the fate of more than 1,000 passengers aboard the RMS Laconia, which was sunk by a torpedo in the mid-Atlantic. His journey takes him across the world, where he faces colossal fish, enormous sharks, and a terrifying creature lurking in the depths of the ocean.