The Ontario women want to try make history this month by relay swimming the length of Lake Ontario over five days of non-stop swimming.
The women, ranging in age from 18 to 61, will begin the relay Tuesday morning and plan to finish in Burlington, 230 kilometres later.
Shields, 61, Nicole Mallette, 48, Samantha Whiteside, 23, and Rebekah Boscariol, 18, have all completed the solo swim across Lake Ontario, a 52-kilometre stretch from Niagara-on-the-Lake to Toronto.
Mona Shariri, 18, the fifth and youngest member of the team by a few months, swam the English Channel last year.
A trip across the length of Lake Ontario by a relay has never been completed. The "traditional" crossing, first completed by a 16-year-old Marilyn Bell in 1954, is usually considered gruelling enough - an overnight solo swim through cold and often rough waters.
Since Bell's swim, the crossing has been successfully completed 56 more times - the majority by women.
But this swim - both for its sheer length and its relay approach - will be "absolutely, totally different", Nicole Mallette told a news conference held Saturday at the shore of Lake Ontario.
"A traditional Lake Ontario crossing we sort of have an idea of what we're doing," she says, wearing a sweatshirt emblazoned with the team's name, "Because Girls Can", above a pink and blue wave. "What we're doing this time, no one's done it before, so we really have no idea what to expect."
And they're itching to get into the water.
"I'm pumped, I'm excited, I'm nervous, I'm every emotion you can possibly think of."
The swim is the result of months of planning, training and logistics, says Mallette, following a "what if?" conversation last fall that quickly sucked in swimmers, coaches and crew.
Four different sailboats and three zodiacs will track the women's progress and provide a place to rest and eat when they're not in the water, she said. They'll also ferry fuel, food, and crew - 30 people on land and water, including the swimmers.
But Mallette says they know well that for all their planning, anything can happen: the team also has plenty of failed crossings behind them - and weather in particular can cause plans to go awry.
"Temperatures are going to fluctuate while we're in the lake, we're just going to have to deal with it," she says. "As I say, we put our big girl panties on and suck it up!"
The team said having the support of the other team members - and not a little competitive spirit - will help them keep swimming.
They're also attempting to raise $300,000 for Because I Am A Girl, a charity to promote rights and opportunities for girls in Canada and abroad.
But now, the planning and preparations are done, and all that remains is getting back in the lake.
"We're ready," says Samantha Whiteside.