Sun has also won plenty of other titles at Asian and World Cup events and, along with badminton player Lin Dan, is one of China’s most popular male athletes.

However, his career has not been without its low points, including a doping scandal and minor trouble with the law.

Here, we look at some of the highs and lows of Sun’s eventful career, which no doubt has many more tales to tell.

THE BEST

World Championships, 2011

Three years prior, Sun finished 28th in the men’s 400m freestyle and eighth in the 1500m freestyle at the Olympics. At the time he was barely on the radar of the leading men’s swimmers but the 2011 world championships in Shanghai changed all that. After finishing second to South Korean Park Tae-hwan in the 400m, Sun won his first major world title in the 800m freestyle. Two days later, he went even better by beating Australian Grant Hackett’s 10-year-old world record in the 1,500m by clocking 14:34.56 on his way to the gold medal. At 19, Sun had announced himself as a truly world-class swimmer.

Olympic Games, London 2012

His debut Olympics in Beijing was largely forgettable but he was 16 then and by 2012 he had emerged as the world’s leading men’s distance swimmer and was a favourite for any event he entered. Such was the case with the 400m and 1500m events at the London Olympics. China had multiple women’s gold medallists but no male swimmer had ever climbed to top podium at the Olympics. Sun was to be the first as he took gold in the 400m freestyle. Though he finished second to Park in the 200m, he was favourite in his pet event, the 1500m.

And Sun did not disappoint. But it wasn’t the perfect start to the race as Sun dived into the pool after a step-down command. He could have been disqualified for a false start but the judges ruled that the dive was because of the noise of fans. Sun went on to dominate the race and smash the world record by more than three seconds for his second gold of the Games.

World Championships, 2017

Sun had won gold in the 200m freestyle at the 2016 Olympics in Rio de Janeiro but the Games overall was a disappointment for the Chinese swimmer, who went to Brazil with higher expectations. Particularly galling was his defeat by Australia’s Mack Horton in the men’s 400m freestyle with the preamble to the race marred by name-calling and accusations of cheating from both sides. Horton had accused Sun of splashing water on his face during practice and the Australian also called him a “drug cheat” because of a secret suspension he served in China for testing positive. So Sun had something to prove when he lined up against Horton in the men’s 400m final in Budapest, Hungary in a race dubbed “War on the Water II”. In the end, it was a rout as Sun won by more than two seconds with Horton taking the silver. Sun, who also won the 200m freestyle gold in Budapest, was once again the pool’s premier male distance swimmer.

THE WORST

Party boy

In February 2013, Sun managed to get himself embroiled in a tabloid news-type scandal involving a secret flight attendant girlfriend that resulted in him missing training and putting the job of his coach in danger.

Sun posted pictures of Nian Nian online and his coach, Zhu Zhigen, was furious because he felt the relationship would damage the swimmer’s performances in the pool. It was reported that Sun was “convicted” of missing training and casting his sport in a bad light, putting pressure on Zhu. Adding to the controversy were accusations that Sun paid more attention to his burgeoning commercial activities than training. Xinhua wrote at the time: ““Aside for a reported love affair with an air hostess making headlines very recently, Sun has systematically been skipping training sessions and instead has indulged in commercial activities for over 40 days.”

Sun was fined one month’s allowance and prevented from engaging in commercial ventures. Chinese media reported in 2016 that Sun was the highest earner among mainland athletes, with income of US$69 million.

Detention

Sun reportedly spent seven days in “administrative detention” after being involved in a traffic accident in November 2013 in his native Hangzhou and then failing to produce a driving licence. Sun was not injured after the borrowed Porsche Cayenne SUV he was driving in was involved in a collision with a bus. He was also fined 5,000 yuan (HK$5,800). In the aftermath of the accident, Sun was temporarily banned from any business-related activities, the national swimming camp and all competitions. “I should have been a role model as an athlete and a public figure but I failed my responsibility,” he later wrote on Weibo. “I am deeply sorry for what I have done and will reflect on my behaviour. Because I have been focusing on training and competition, I had only a hazy knowledge of the law, which led to my mistake.

“After this incident, I will strengthened my knowledge and study of the law to prevent such a thing from happening again. I hope that everyone will take this as a warning and give me an opportunity to correct my mistake.”

Ban for doping

In May, 2014 Sun was hit with a three-month ban after testing positive for the stimulant trimetazidine, which had only four months earlier been added to the World Anti-Doping Agency’s list of banned substances. What made it worse was that the Chinese Swimming Association failed to announce Sun’s penalty until after he served the ban, leading to an international outcry and tainting the swimmer’s reputation. Horton’s “drug cheat” accusations were based on the CSA’s decision to keep Sun’s ban a secret. It could have all been avoided because the drug’s performance-enhancing effects are deemed ‘inconsequential” when taken out of competition and Sun could even have filed for medical exemption because he needed it to combat the episodes of heart palpitations he has suffered since 2008. In the aftermath of the revelations, Swimming Australia stopped Sun from working with their coach Denis Cotterell and he was prevented from practising at SA official training centres.