"There is hardly another Hammer picture [that] features the sheer madness within, like a psychedelic dream come to life or something straight from the mind of Terry Gilliam ... the sheer unpredictability ... keeps you glued to your seat and your eyes on the screen." – The Telltale Mind

The passengers of an old freighter en route to South America find that their voyage is truly damned! The nightmare begins when Captain Lansen (Eric Porter) attempts to transport illegal explosives and their rusty tramp steamer becomes stranded in the vast floating swamp of the mysterious Sargasso Sea. Under the cover of night, the terrified travelers encounter unspeakable monsters, man-eating seaweed, vicious mutant pirates and stupendously endowed women. All aboard for this "marvelously absurd, straight-faced anthology of comic-strip plots, dialogue, devices and special effects" (The New York Times)!