The Australia Day ambassador, who will lead celebrations across Sydney Harbour on Monday, made the rescue of the father in his 40s at Werri Beach beach south of Kiama after patrol hours.

She told Fairfax Media that the man, who didn't speak English and whose family was barbecuing up the beach, would have lost his life if she hadn't spotted him in the dramatic rescue earlier this month.

"It was quite a powerful and notorious rip with a strong sea breeze and it was quite choppy," she said. "He was 50 to 100 metres off shore beyond the breakers in a panic and yelling. 

"He was bigger than me so there were a few risks of getting involved. I had to get him to hold on to my ankle rope which wasn't easy because there was a language barrier. I then lay on the board to paddled him out of the rip. I was able to get back to the breaking waves and we were then washed back to where the sand bar is.

"People came running down from the top to assist. I thought it was so lucky that he could walk back to his family. It could have been a very different story. It was lucky I was in the right place at the right time."

Fitzgibbons is spokeswoman for the Australia Day Council of NSW and will be part of the day's celebrations.

As well as warning of the danger of swimming outside the flags or outside patrol times  she had another safety message for Australia Day.

"I have campaigned a little bit about drinking and alcohol," she said. "I don't drink myself and never have. A good message is to celebrate and have a few drinks but not go overboard and out of control. You don't want anything bad to mar such a fantastic day for all Australians."

She also commented on whether Australia would one day become a republic or if the flag could change.

"We are definitely a strong nation and as we continue to grow possibilities like that will pop up but I'll leave that to the experts for sure," she said. "I don't really have a strong yes or no on that one."

And of the flag: "It's such a strong identity, it would be hard to change at this stage. I just know that when I go and compete when I'm surfing representing our country there's such a big sense of pride."

Jokingly she added: "I don't want the flag to change but I wouldn't say no to a little surfing kangaroo in the corner."

Fitzgibbons is part of the Australia Day Council 'Aussie Fan' campaign, in which celebrities tell the world what is great about Australia.

Socceroos star Tim Cahill posted: "I'm an Aussie Fan because I love my country." Michelle Bridges posted: 'I'm an Aussie Fan because anything is possible here in Australia and we all have the freedom to be our unique selves", and Bindi Irwin said: "I'm an Aussie Fan because we have the most spectacular wildlife, I should know, I live at Australia Zoo."