We weren't counting on swimsuit shopping this late into September, but Ashley Olsen [1] just gave us a good reason to. While on vacation with her sister in France [2], the style setter looked effortlessly cool in a strapless black one-piece swimsuit. That's it. No bells or whistles, crazy cutouts, or strappy back, just an easy, totally versatile suit that would become a staple in anyone's swimsuit drawer.

So, while we highly encourage some necessary Fall shopping [3], we also know a good thing when we see it — and sometimes that means shopping for a swimsuit when it's out of season. Read on to see Ashley Olsen show off the perfect suit you just might be missing.

Norma Kamali Bishop Strapless Swimsuit [4] ($173)

Onia Allie One-Piece Swimsuit [5] ($150)

Seafolly Ruched-Panel Maillot One-Piece Swimsuit [6] ($172)