Tomorrow, Step Up 3D, the third installment of the great dance-movie franchise, arrives in theaters. Step Up’s major accomplishment has been to take the best parts of the dance-movie genre (which are the best parts of the sports-movie genre — natural arc, built-in plot, drama, intensity — plus sex, lots of sex, in forms that include sexual tension, sex itself, and, of course, dancing, which is sex with your clothes on (unless you are Patrick Swayze, in which case dancing is sex with only some of your clothes on), and consistently add riveting, top-notch dancing. (Excellent dancing is not a dance-movie requirement, as Julia Stiles performance in Save the Last Dance exists to prove.) Nowhere is the high quality of movement in the Step Up series as evident as it is in its soaking-wet dance scenes, one of which was the climax of Step Up 2: The Streets, and another of which appears in the upcoming film. Of course, Step Up isn’t the first movie to contain a sopping boogie: On the occasion of the film, please enjoy a slideshow of great moments in dancing while wet.