Michael Phelps recently "raced" a shark, except Phelps didn't swim side-by-side with a real shark. He went up against a CGI shark ... that simulated how fast a shark would swim in a straight line.

Michael Phelps gave his 4×100-meter freestyle relay team a sizable lead in the second leg of the finals to help the Americans claim the gold medal. The win marks Phelps’s 19th Olympic gold ...