It seems the construction boom in bustling Dubai is far from over – already home to several world record-holding projects, including the tallest building (for just a little while longer), the largest shopping mall and biggest man-made island, plans are now afoot to construct what will likely be the world's largest underwater luxury hotel, the Water Discus. Several years ago, we reported on another such ambitious project, Hydropolis, which sadly never got past the blueprint stage.