Big River Man is a documentary about Martin Strel, a Slovenian long distance swimmer. Strel, an overweight, middle-aged man, who proclaims to drink two bottles of wine a day, is an unlikely athlete. But, Strel has swam the length of the Mississipi, the Yangtze, and the Danube before attempting to swim the Amazon in 2007, all in the name of highlighting the pollution of our rivers. The Amazon is 1,000 miles longer than his previous world record of swimming the Yangtze.
The movie is narrated by Strel's son who also serves as his manager, PR person, and caretaker. The beginning of the story is told with levity ("Slovenia is shaped like a chicken") as we follow Strel in his attempt to swim the Amazon but the tone grows more serious as each passing day finds Strel losing his grip on reality and ultimately risking his physical and mental health to accomplish his goal.