He quickly sparked her competitive nature.
"My brother said be there or be square, well I couldn't be square could I? And I'm the swimmer and he isn't."
She concedes that her brother swims for fitness while her training consists of "a last-minute panic. Why did I take the bait from my brother!"
She has not swum in the Auckland harbour before and needs to get a wetsuit to take on the chilly temperatures.
But the cold water is not her main concern.
"I am not worried about that or the ships but things with fins I want to avoid.
"I am an ex-surf lifesaver as well and I never used to think about [sharks] years ago but now I do since I became a mother."
Clement says she will definitely win against her brother in the Harbour Crossing, otherwise she would never hear the end of it.
Competing in the Round The Mount Swim in January is something she would like to do this summer once she safely makes it to the Viaduct from Devonport on November 17.
Ahead of her brother, of course.