If your data are three dimensional cubes then GAIA allows you to display image planes and also plot spectra from the hidden dimension. It can also display a full volume visualisation, or just display the whole cube as a stretched single image.
The default method is to open up data-cubes using the cube toolbox, that gives you control over which slice you want to view and enables interactions on the main window for extracting and plotting spectra from the hidden dimension (and many other tasks for collapsing to white-light images etc.), this toolbox also provides access to the volume visualisations. You can go this mode directly by selecting the "Open cube..." item in the "File" menu.
The cube toolbox is described more completely in it's help page.
If you want to display the cube as a stretched out series of images running from the bottom to the top of the image display you will need to start GAIA with the -check_for_cubes option set to 0, and have an NDF format cube.