61-year-old Martin Strel will set off today, World Water Day, from Long Beach, CA, in an attempt to swim around the world. Strel, originally from Slovenia, is a long distance swimmer who gained notoriety from the 2009 documentary "Big River Man" in which he successfully swam the length of the Amazon River in 2007; Strel covered 3274 miles in 66 consecutive days. He is the only person to have swum the full length of the Amazon, Yangtze, Mississippi, Danube, and Parana Rivers. Photo courtesy of strel-swimming.com Strel set off on World Water Day in order to raise awareness for clean water and the pollution of rivers around the world. To swim around the world, he is hoping to swim nearly 25,000 miles and travel through 107 different countries in 450 days. He will be swimming between five and twelve hours a day and will have an escort boat in case of emergencies. According to Strel's team, one reason for his success is that his body does not produce Lactic Acid, the chemical that causes muscle fatigue after exercise. The estimated finish date for the swim around the world is July 2017.