Shot this a little while ago from Burano.  You can see when you zoom in the smoke stack spewing bunker fuel fumes into the air; you can see the gigantic scale on the cruise ship compared to the Venetian skyline.   It’s a monstrous floating city that dwarves the delicate city next to it.

It’s plain as day why the cruise ships need to be docked away from Venice.  Click for a full size image that really drives the point home.