Where is it

the ship is the island, they put a fake island on top of the ship, people are in the island/ship so they can't be seen from the outside

Are you positive about that? Not saying it'simpossible but I thought this was just a picture of an actual camouflaged ship near enough to the island. You can plainly see the straight edges and flat sides, seems odd to put a whole island on a ship but not bother hiding a third of the ship

Sorry if you were kidding and I took you seriously, the scale of the trees would make this the largest ship every made, there's no way

i was not kidding, but thankyou for explaining it to me @nicengelman