Michael Phelps Explains Why He’s Racing a Shark

Michael Phelps of the United States celebrates winning gold in the Men's 200m Butterfly Final on Day 4 of the Rio 2016 Olympic Games at the Olympic Aquatics Stadium on August 9, 2016 in Rio de Janeiro, Brazil.
Michael Phelps of the United States celebrates winning gold in the Men's 200m Butterfly Final on Day 4 of the Rio 2016 Olympic Games at the Olympic Aquatics Stadium on August 9, 2016 in Rio de Janeiro, Brazil. Clive Rose/Getty Images