Lumina Films has snapped up worldwide rights to “Big River Man,” John Maringouin’s docu about Slovenian swimmer Martin Strel’s 66-day plunge down the Amazon. He’s accompanied by his son, Borut, as they swim the most polluted rivers in the world.Revolver Entertainment took U.K. distribution rights. London-based Lumina Films is headed by Samantha Horley, who will rep sales on “Big River Man.” Docu’s producers are Molly Lynch, Maria Florio and Molly Hassell. Exec producers are Olivia Newton-John, Mickey Cottrell and Kevin Ragsdale. Lumina also reps Puerto Rico’s Oscar submission, “Maldeamores,” a bittersweet comedy exec produced by Benicio del Toro.