Tips:
The Iray Scene loads with a volumetric cloud softly touching the lower ends of the isles.
You can simply move it higher (Y-axis up) to get a more misty look.
Or intensify the density with the “Density Multipier” option in the Surface Settings.
If you want more isles in the scene (e.g. floating in the background) you can simply load the scene twice and move the duplicate group to where you need it.
If you work with the 3Delight version you should delete the duplicate Skysphere and lights though.
Have fun rendering!