The sisters from Katikati are part of the Mount Maunganui Lifeguard Service under the guidance of coach John 'Spindles' Bryant. Wearing the New Zealand uniform together is a dream come true.
Libby, 18, made her debut for New Zealand last year at the world champs held in the Netherlands.
"It was a pretty special moment to get my first black cap but I am really excited for this competition. The step up from club racing to international racing is huge, just so much more professional, but it is also about having fun," she said.
"I race best when I have fun being surrounded by a team. This is what we train for to have these times to be in the New Zealand team."
Competing at the Mount Main Beach will cede the New Zealand athletes a small advantage but particularly the Western Bay team members.
"It is my home beach, where I have done all my hard training so to actually be able to race there in an international competition is going to make it even more special," Libby said.
For Tessa, 17, it will be her first time representing New Zealand and she can't wait.
"When I was younger I was not really into sports as I was scared of the waves but my coach Spindles got me going and I realised I could do okay in the swim and stuff.
"After that I got better and realised I could make the team. I started beating Libby, winning at the nationals in two swim races," Tess laughed looking over at her sister.
Libby says it helps them both they have such a friendly rivalry.
"We push each other so much. Obviously I don't want her to beat me but we are both trying to build to have a big summer."
Junior Black Fins coach Matt Cairns, who also mentors the Papamoa surf team, is in his first year in the role.
"I am really excited and this age group is one I really enjoy working with. The nature of a junior team is that for a lot of them it is their first experience in the team," he said.
"Australia are the reigning champs for the youth division but there are some talented athletes out there from each of the countries so we are looking forward to challenging ourselves against them."
The first test begins at 8.20am today