World champion Emily Seebohm had led tributes for Kenneth To, saying the former Australian Dolphins team member's sudden death has rocked Australian swimming.
A 12-year Dolphins team veteran, Seebohm said she was still coming to terms with news that world titles silver medallist To had died aged 26 after becoming ill during training in Florida.
The cause of death was not immediately clear.
Seebohm had bonded with To on several national team campaigns but never competed with the medley and sprint champion at an Olympics, which
"It has hit us hard," she told AAP.
"Me especially. I have been on many teams with Kenneth before.
"I know his big goal was getting to an Olympics, that was what he dreamed about doing.
"Now we have that chance we should not take anything for granted and just be thankful for what we have got."
To contested two world titles and the 2014 Glasgow Commonwealth Games for Australia, claiming silver as part of the 4x100m medley relay squad at the 2013 world championships.
He switched allegiances to the country of his birth, Hong Kong, in early 2017 in a bid to crack the Tokyo 2020 squad.
To narrowly missed out on 2012 Olympic selection for Australia after finishing fourth in the 200m medley final at the trials just weeks after having his appendix removed.
A long term back injury forced To to withdraw from Australia's 2016 Olympic trials.
"Not only the Australian but also the Hong Kong team has lost a warm hearted person and a great role model in our sport," backstroke champion Seebohm said.
To originally moved from Hong Kong to Sydney when he was two.
He claimed six medals including one gold at the 2010 Youth Olympics in Singapore and in 2009 broke Ian Thorpe's decade-old Australian record in the 200m individual medley before earning senior Dolphins honours.
Since switching allegiances to Hong Kong in 2017, To placed sixth in the 100m IM medal race at the 2018 world short course titles in China in December - his first individual final at a major meet in six years.
To was in Florida for a three-month training camp with the Gator Swim Club at the University of Florida in Gainesville before being taken to hospital after claiming to feel unwell following his warm-up.
