Four-time Olympic gold medallist Ariarne Titmus has announced her shock retirement from swimming, revealing the seed was sewn by her cancer scare before the Paris Games.

The 25-year-old, who grew up in Tasmania but moved to Queensland as a teenager, will retire as one of the greatest distance swimmers of all time.

“It’s a tough one but one that I’m really happy with,” she said in an Instagram video post on Thursday.

“I’ve always loved swimming … but I guess I’ve taken this time away from the sport and realised some things in my life that have always been important to me are just a little bit more important to me now than swimming.”

Before the Paris Olympics, Titmus had surgery to remove two benign tumours after a large growth was found on her right ovary. She described that health scare as a “turning point”.

“A turning point for me, or a time when a switch was flicked, was in the lead-up to the Paris Games. I went through some health challenges, which quite frankly really rocked me mentally,” she said.

“It probably was the first time where I considered some things outside of swimming.

“Delving more into those health challenges, I’ve really had to look within and think about what’s most important to me – and beyond swimming, I’ve always had goals in my personal life. But swimming has always been most important up until this point, and I’ve just realised that those goals and what I want in my future is now more important to me.”

“More than anything, I’m excited for what’s next.”

At the 2024 Paris Olympics, Titmus achieved a historic third individual Olympic gold medal, winning the 400-metre freestyle in what was dubbed “the race of the century”. She defeated the event’s two other previous world record-holders – American all-time great Katie Ledecky and Canadian swimming prodigy Summer McIntosh.

In doing so, Titmus became the first Australian female athlete since Dawn Fraser in 1964 to win back-to-back gold medals in the same event.

Titmus credited Ledecky with pushing her to become a champion athlete, naming her 2020 Tokyo Olympics, when she edged the 400-metre world record-holder, as her greatest achievement.

“There’s nothing like the first – Tokyo – going in as what was deemed the underdog. But I knew in myself I could win, and to come from behind and win in Tokyo against the GOAT, that feeling will sit with me forever,” she said.

“To win Olympic gold; it just didn’t have to be the best in the world I had to beat the greatest ever in the world. And, you know what, someone could look at that as a burden, but I absolutely looked at it as a blessing because I can say without a doubt, without facing Katie, I wouldn’t have been the athlete that I am.”

Titmus, Tasmania’s 2025 Young Australian of the Year, steps away from the sport as the 200-metre world record-holder. She has also won a staggering haul of 33 international medals, including eight Olympic medals (four gold, three silver and one bronze), and four world titles.

She said she hoped to work more in broadcasting and public speaking. She also wants to give back to swimming, particularly working with young athletes from regional areas.

-AAP