Mathematica 9 introduces the visualization primitives Raster3D and Image3D. These 3-dimensional data expressions add a new dimension to our image processing capabilities and it is now possible to display these data sets via interactive volume rendering. In this talk we will explain the principles of volume rendering and the art of constructing the right transfer functions. We will explore the caveats and extravagant possibilities of this new visualization modality and apply it to real world data as well as to synthetic computation results.