Bruce finished treatment for breast cancer in March.

"I hesitated at first but then I went you know what, why not."

She hadn't heard about the swim, which raises money for Love Your Sister and Lifeline charities, until she met Ruth Lindbeck at the hairdressers last week.

Lindbeck's husband Peter was one of the inaugural nude swimmers in 2017.

"Ruth was telling me about the swim, and how much money it raised last year, and here we are."

Bruce, Lindbeck and several other hardy souls braved the waters of Lake Burley Griffin on Monday to launch the swim, which will take place at 7.12am on Friday, June 21, on the winter solstice.

Lindbeck was convinced to do the swim after her husband convinced her it was one of the best things he has ever done.

"Karina and I only met last week so it's been nice to be here for each other."

Ian Lindeman, chief organiser of the event, was inspired to host a Canberra event after attending Hobart's Dark Mofo Nude SolsticeSwim in 2016.

"Last year we had 69 people swim and we raised $10,700 for Lifeline and Love Your Sister and this year we're shooting for $30,000.

"We'd like to get about 300 people here this year, we've already had more people register."

Entry is $30, to the charity of your choice