Queensland, Australia, natives Ilona Hamer and Peta Heinsen—the sisters behind swimwear label Matteau—are no strangers to big open skies, salty air, and sandy beaches. It was their outdoorsy upbringing—along with their half-Croatian, half-English heritage—that fueled the need for an elegant yet understated bikini to complete their look. That and the fact that they couldn’t find a simple suit Down Under that wasn’t overly skimpy and sexy. “We wanted to create the equivalent of the perfect ‘jeans and a T-shirt’ for the beach,” says Heinsen of the sisters’ swoon-worthy line of swim- and resortwear, now sailing stateside with a little help from celebrity supporters including  Laura Harrier and Rosie Huntington-Whiteley, among others.

Now three years in, Hamer and Heinsen are dipping their feet into the ready-to-wear world with easy cover-up pieces—a gauzy, boyish button-down shirt and a long, loose floaty dress—designed exclusively for Net-a-Porter. The idea, as the duo tells it, was to make beachwear an extension of a modern wardrobe. “We just want to create wonderful additions for a traveling wardrobe,” says Hamer of the Spring collection, which drew inspiration from the work of Robert Motherwell, John Chamberlain, and Barbara Hepworth. “These are pieces to wear over your swimsuit or mix with your Céline and Lemaire,” adds Heinsen, who has plans to take her new pieces to Mexico and Belize. And that’s not to say the sisters want you to cover up. They hope to help women feel their best while baring (almost) all in the one clothing item that seemingly strikes fear in ladies around the world. “When a customer tells us she hadn’t been in a bikini in five years, took the plunge in Matteau, and never felt better,” says Heinsein, “well, that’s just magic.”