Park began swimming at the age of 5 when his doctor suggested it would be good for his asthma. He began his competitive swimming career at the age of 7, earning several medals in junior competitions. This early success led to Park's selection to the Korean Swimming Federation as a national team member in 2003. At the 2004 Summer Olympics, however, Park was disqualified for a false start in the preliminary heat of the men's 400m freestyle competition. However, shortly thereafter at the 2004 Fina Swimming World Cup, Park was the runner-up in the men's 400 meter freestyle event. Park continued his competitive success in subsequent years, most notably at the 2006 Asian Games in Doha, where he won three golds, one silver and three bronze medals, the most medals won by a single athlete at the Games. He also set two Asian Records. For his success, Park was named an Athlete of the Games. At the 2006 Pan Pacific Swimming Championships in Victoria, Canada, Park won two gold medals (in the 1500 meter freestyle and the 400 meter freestyle) and one silver medal (200 m freestyle). Park was named the 2006 Pacific Rim Male Swimmer of the Year by Swimming World Magazine, beating out Olympic medalist (and 2005 awardee) Australian Grant Hackett for the honor. At the 2008 Summer Olympics, Park won a gold medal in the 400 meter freestyle event and a silver medal in the 200 meter freestyle event. In swimming 1:44.85 in the 200m freestyle final, Park joined Michael Phelps, Ian Thorpe, and Pieter van den Hoogenband as the only men to have ever swum under 1:45 in the event. Much of the press coverage surrounding Park's successes emphasize the fact that these are the first Olympic medals in swimming for South Korea.
Just after a stunning victory against idol Grant Hackett in the men's 400m freestyle at the 2007 World Aquatics Championships in Melbourne, Park decided to train alone in Sydney, Australia as his own '500-day project', parting with his personal managing team in December 2007. He then joined the Korean national team training base in February 2008 to prepare for the 2008 Beijing Olympics. Under Park's personal coach Roh Min-sang and other members of the coaching staff, the national team trained in Malaysia (February 2008) and Guam (May 2008) to prepare Park for his second attempt at the Olympics. He qualified for competition in the men's 200 meter, 400 meter and 1500 meter freestyle events.At the 2009 World Aquatics Championships, Park surprised many after failing to qualify to swim in the finals of the 200 and 400 m freestyle. Some blame Park's poor performance on his decision to wear Speedo's LZR Racer in the championships.
Personal bests
* 100m 48.70 (2010) 2010 Asian Games Final; won the gold medal
* 200m 1:44.80 (2010) Asian Record 2010 Asian Games Final; won the gold medal
* 400m 3:41.53 (2010) 2010 Asian Games Final; won the gold medal
* 1500m 14:55.03 (2006) 2006 Asian Games Final; won the gold medal
Park Tae Hwan Freestyle