A tramp steamer carrying a cargo of illegal explosives becomes stranded in the mysterious region of the Atlantic known as the Sargasso Sea, where giant crabs and jellyfish, killer seaweed, and some Spanish conquistadors are among the perils awaiting the ship's passengers, in this sci-fi thriller from Hammer. Eric Porter, Suzanna Leigh, Hildegard Knef star. 89 min. Widescreen; Soundtrack: English; Subtitles: English.