Adelaide's Brighton Beach was inundated with a sea of blonde wigs, sunglasses and white swimwear for the annual Marilyn Jetty Swim.
The 10th anniversary of the event achieved record numbers, with 513 Marilyn Monroe impersonators attending — up from 300 participants last year.
The event has raised $1 million for Cancer Council SA since its inception, including more than $220,000 this year alone.
Founding Marilyn, Sarah Tinney, started the event after losing her mother to cancer in 2007.
She believed dressing up as the iconic Marilyn Monroe was an empowering and fun way to raise money for cancer research.
"Every year when I see new Marilyns come, and they have their stories and I can see where they are at, they're at day one of losing somebody they love," Ms Tinney said.
"I go back there, and I know exactly how they're feeling.
"And I love that there's something that we can all do together, even if it's kind of wild and not what you expect … because grief isn't orderly, grief isn't predictable.
"Grief's a little bit weird as well."
Reaching the $1 million fundraising milestone was "very surreal" for Ms Tinney.
"Nobody could have anticipated this kind of growth," she said.
The event attracted people of all ages from across the country to support the cause, most donning blonde curls and wearing Monroe's trademark sunglasses and white swimsuit.
One woman travelled from Cairns to take part.
"I had breast cancer five years ago, so I know it's a worthy cause," she said.
"I'm right behind everyone and these gorgeous, blonde bombshells."
Surf Living SA kept a watchful eye on those who swam or paddled around the jetty as part of the annual 400 metre swim, turning the ocean into a sea of smiling faces and inflatable swim rings.
Cancer Council SA Kerry Rowland said organisers were working towards making the event even "bigger and better" next year.