To competed for Australia until 2016, before switching nationality to represent his native Hong Kong.

The Hong Kong Sports Institute (HKSI) confirmed To’s death, which came after a training session in the United States on March 18.

“The HKSI was deeply shocked and saddened to learn of the sudden passing away of elite swimmer Kenneth To,” an HKSI statement read.

“He had been undergoing a three-month training programme with the Gator Swim Club of the University of Florida.

"He felt unwell at a training session and was taken to hospital where sadly, he passed away.

“Kenneth was an outstanding elite athlete who holds 17 Hong Kong records.

“He had been an Elite Scholarship Athlete at the HKSI since August 2016.

“He was extremely popular and loved by his team-mates and competitors. 

"Kenneth was known as a truly exceptional person – warm, funny and kind.

“His sudden passing is a huge loss to local sports.

“The HKSI extends our deepest condolences to Kenneth’s family, team-mates and coaches.”

To competed for Australia at the Singapore 2010 Youth Olympics, where he secured six medals.

This included gold in the men’s 4x100 metres relay, as well as three silver and two bronze medals.

He won the men’s overall title in the International Swimming Federation (FINA) Swimming World Cup in 2012, making him the only Australian man to have achieved the feat.

To then secured one silver and two bronze medals at the FINA Short Course World Championships in 2012, before winning 4x100m medley relay silver at the Long Course World Championships in Barcelona the following year.

He celebrated men’s 4x100m freestyle relay gold at the Glasgow 2014 Commonwealth Games, alongside winning silver for Australia in the 4x100m medley relay.

After injury prevented him from competing at the Rio 2016 Olympic Games, To opted to switch nationality.

His first international event competing for Hong Kong came at the Taipei 2017 Summer Universiade, while he also represented the territory at last year’s Asian Games in Jakarta.

To had been training in the United States as part of his aim to qualify for the Tokyo 2020 Olympic Games.

“Owner of many Hong Kong swimming records, Kenneth To was a reference and example for the youth in the territory,” a FINA statement read.

“In this moment of grief, FINA sends its heartfelt condolences to To’s entourage and to the entire swimming community in Hong Kong.”

Swimming Australia national head coach Jacco Verhaeren also paid tribute to To, who he described as an exceptional team-mate.

“We are all very shocked and saddened by Kenny’s passing and wish his family and friends strength at this incredibly difficult time,” Verhaeren said.

“He was a much-loved team member with a determined spirit and wonderful personality, so he will be missed by his peers, coaches and staff.

“Personally, I was fortunate to work closely with Kenny in the lead up to the 2014 Commonwealth Games.

“In that year he suffered a bad back injury after qualification and although he could have pulled out, he refused to give up on the team and did everything he could – it showed the resilience that was instilled in him and was a testament to his character.”

South African star Chad Le Clos was among the leading swimmers to offer their tributes to To.

“RIP brother, so sad to hear the tragic news,” Le Clos said.

“You were a great example to everyone and will never be forgotten.”