It's one of three fabulous beaches on Siesta Key, a barrier island in the Gulf of Mexico off the coast of Sarasota. According to the World's Best team, Siesta Beach stands out thanks to its "powdery, blindingly white sand, made up of 99% pure quartz from the Appalachian Mountains." And it's true, unlike many other beautiful beaches in the US, Siesta's sand has a silky, sugar-fine texture: "The main attraction of Siesta Beach is the uniqueness of its white powdery sand that you don't see just anywhere."