Explorer Thor Heyerdahl and his ten-man crew sailed their reed boat, the Tigris, over routes he believes were followed by Sumerian traders 5,000 years ago. The film goes beyond science to focus on the man, Heyerdahl, in an effort to explain what motivates him to risk his life in the search for knowledge.

Ra [also known as The Ra Expeditions] is a 1972 documentary film directed by Lennart Ehrenborg and Thor Heyerdahl about the expeditions organised by Thor Heyerdahl in 1969 and 1970 in attempt to cross the Atlantic on papyrus boats. It was nominated for an Academy Award for Best Documentary Feature.