Klaus Kinski delivers a remarkable performance as the central character—a somewhat eccentric opera enthusiast who feels compelled to introduce his passion for Verdi, Bellini, and Puccini to a remote jungle community. He understands that sharing this love requires money, which he intends to acquire by exploiting rubber trees deep within the Amazon. To achieve this, he and Molly, portrayed by Claudia Cardinale in a limited role, manage to gather enough funds to purchase an old, run-down steamer from Don Aquilino, played by José Lewgoy, and embark on a journey into unknown territory with a ragtag group of individuals facing rapids, insects, and potential threats. However, there's a significant obstacle to his carefully laid plan: the region he wants to exploit is incredibly difficult to reach, demanding considerable engineering skill to overcome. Fortunately, they encounter local people who possess a legend about a yellow-haired man sent by their gods—a description that conveniently fits Kinski’s character—and they agree to assist him in moving the boat uphill, quite literally, from one river to another. The question is whether he can maintain the loyalty of his superstitious allies and his easily distracted crew long enough to achieve success and then return to some semblance of civilization. It's true that the film's continuity isn’t always consistent; it seems to make a mockery of John Wayne’s timekeeping, but considering it was filmed in Peru and on the Amazon River itself, this is an impressively executed production that truly places you within the challenges faced by the characters and explores the personality of a man who skillfully navigates the line between clear-headedness, inventiveness, and madness. The film does feel somewhat drawn out, with several scenes contributing little to its overall momentum, but Kinski and Herzog flourish in this oppressive heat and humidity, creating an engaging and thrilling travelogue unlike anything else available.

Source on TMDB