This Floating Island is a Lego Tensegrity Sculpture built by LaughingJelly. This scene would fit in perfectly with Ninjago. The floating island is carefully balanced over a serene lake. The optical effect is actually created with a system of tension. The three Lego ropes / strings are holding the island up. In order to get the length just right the designer has hidden a technic pin inside the rocks, and has coiled the center string until the effect works. It can hold a surprisingly large amount of bricks / weight, but any sort of horizontal pressure will cause everything to fall over. The sheer amount of grass and vegetation makes the scene look like a hidden garden. And, the whole thing has been built on top of a detailed base. A detail that a lot of designers skip over.
You can find more info about this Floating Island Lego MOC over here: https://www.reddit.com/r/lego/comments/haqug2/i_made_a_japanese_floating_island_it_took_weeks/
A lot more Lego Tensegrity builds can be found on EveryDayBricks over here: http://everydaybricks.com/tag/tensegrity/