Princess Maria-Olympia of Greece has been known to show off her stylish looks on Instagram. That gold Michael Kors dress she shopped right off the catwalk? She worked it from every angle. But for her birthday, the princess went all out, posing poolside underneath a celebratory sign in Mykonos. Maria-Olympia's swim look is, of course, just as fashion-conscious as the rest of her outfits. So far she's flaunted a Missoni playsuit, green bandeau bikini, and lacy black cover-up. Read on for a few snaps, then shop an inspired, royally approved Summer wardrobe.