1912:Duke Kahanamoku, USA, 1:03.4
2008:Alain Bernard, France, 47.21
For many years, the 100-meter freestyle was the ultimate test for measuring the fastest swimmer on earth. The 50-meter swim has since taken the title, but for our purposes, Duke Kahanamoku's 1:01.4 second hundred free in 1912 helps us prove a point. Alain Bernard, the 2008 winner in this event in Beijing swam it in 47.21. You could add Usain Bolt's 100-meter sprint to Bernard's swim and they'd still beat Duke by over four seconds.