A 20-year-old Coughlin poses with her four gold medals after the 2002 Pan Pacific Championships.
Natalie Coughlin
Natalie Coughlin poses in her Cal swimsuit during an SI photo shoot in May 2003.
Natalie Coughlin
Coughlin competes in the 100m butterfly during the 10th World Swimming Championships in Barcelona in 2003.
Jenny Thompson, Lindsay Benko, Natalie Coughlin and Amanda Beard
The women's 4x100m relay team (from left) Jenny Thompson, Lindsay Benko, Natalie Coughlin and Amanda Beard show off their silver after claiming second at the 10th World Swimming Championships in Barcelona.
Amanda Beard, Michael Phelps, Jenny Thompson and Natalie Coughlin
Olympians (from left) Amanda Beard, Michael Phelps, Jenny Thompson and Natalie Coughlin pose on the Athens beach during the 2004 Olympics.
Natalie Coughlin and Amanda Beard
Coughlin (left) and teammate Amanda Beard throw the ceremonial pitch at a Dodgers game on Sept. 15, 2004.
Natalie Coughlin
Coughlin won gold in the 100m backstroke at the Athens Olympics. She went on to defend her medal at the Beijing Olympics, becoming the first woman to defend her medal in that event.
Natalie Coughlin, Dana Vollmer, Carly Piper and Kaitlin Sandeno
Team USA's 4x200m relay teammates (from left) Natalie Coughlin, Dana Vollmer, Carly Piper and Kaitlin Sandeno celebrate with their gold medals after setting a world record in the event at the 2004 Olympics.
Natalie Coughlin
Coughlin celebrates after setting a world record in the 100m backstroke at the World Swimming Championships in Melbourne in March 2007.
Al Roker, Katie Couric, Natalie Coughlin and Matt Lauer
Coughlin appeared on "The Today Show" to blow out her birthday candles on Aug. 23, 2004
Natalie Coughlin
Coughlin dives into action at the start of the 100m freestyle finals during the Santa Clara International Meet in 2006.
Natalie Coughlin and Margaret Hoelzer
Coughlin (left) and teammate bronze medalist Margaret Hoelzer celebrate during the medal ceremony for the 100m backstroke final during the Beijing Olympics.
Garrett Weber-Gale, Ryan Lochte, Dara Torres, Aaron Piersol, Katie Hoff, Margaret Hoelzer, Cullen Jones and Natalie Coughlin
Coughlin (far right) poses with part of Swimming Team USA before the 2008 Olympics.
Natalie Coughlin, Kara-Lynn Joyce, Lacey Nymeyer and Dara Torres
Coughlin (far left) and teammates Kara-Lynn Joyce, Lacey Nymeyer and Dara Torres flash their medals after taking second in the 4x100m freestyle relay at the Beijing Olympics.
Amanda Beard, Michael Phelps, Natalie Coughlin and Kate Ziegler
Amanda Beard, Michael Phelps, Coughlin and Kate Ziegler debut the new high-tech swimsuits used in the 2008 Games.
Alec Mazo and Natalie Coughlin
During her swimming hiatus, Coughlin appeared on "Dancing with the Stars" in 2009 with partner Alec Mazo, and competed in the first five episodes.
Natalie Coughlin
During the year and a half she took off from swimming, Coughlin arrives at US Weekly's Hot Hollywood party on Nov. 19, 2009.
Natalie Coughlin
Coughlin poses for a portrait at the Meet Team USA Media Summit, one of many stops on her way to her third Olympics.
Natalie Coughlin
Coughlin, the first American woman to win six medals in an Olympiad, poses during the Meet Team USA Media Summit 2012.
Natalie Coughlin
The three-time Olympian attends the London 2012 Olympic Games announcement in New York City in 2012.