Talk about one gorgeous flashback! Late last week, this photo of Princess Diana from 1990 surfaced on Instagram, and it couldn’t be more stunning. In the vintage snap, the Princess of Wales lives up to her status as a style icon, showing of her glam yachting style in a patterned bikini, knotted purple button-down shirt, and oversize sunglasses.

The image was shared by Giancarlo Giammetti, the honorary president of the Valentino Fashion House and longtime partner of designer Valentino Garravani, as a throwback Thursday. “Summer is here TBT princess Diana on the TMblue 1990 #princessdiana #rosariosaxecoburg,” Giammetti captioned the photo.

Princess Diana isn’t the only royal featured in the picture, which was taken aboard Garravani’s T.M. Blue One yacht. Rosario Saxe-Coburg, wife to the Prince of Preslav, Bulgaria, stands nearby in a white T-shirt. And we have to wonder, is that adorable young boy next to Diana Prince William? Either way, the late and beloved Princess of Wales looks as stylish as ever in this casual summer photo, and we can’t help but miss her effortless and inimitable elegance.

Click through our gallery to see Princess Diana’s most iconic looks ever.