Exploration and navigation in multimedia data hierarchies (e.g., photos, music) are frequent tasks on mobile devices. However, visualization and interaction are impoverished due to the limited size of the screen and the lack of precise input devices. As a result, menus on mobile devices do not provide efficient navigation as compared to many innovative menu techniques proposed for Desktop platforms. In this paper, we present Wavelet, the adaptation of the Wave menu for the navigation in multimedia data on iPhone. Its layout, based on an inverted representation of the hierarchy, is particularly well adapted to mobile devices. Indeed, it guarantees that submenus are always displayed on the screen and it supports efficient navigation by providing previsualization of the submenus.