How do you get the secret worlds on new Super Mario Brothers 2?

Answer 1

There is a special key when you defeat bowser, but you have to be shrunk down to mini size to do so 🐼

Answer 2

To go to special world you have to finish W8.Then you go to world one and jump in the tube on the map

Answer 3

in the underground world you go to the back of the final tunnel (on top of the bricks) and there is 3 tunnels pick one and go down in one to go to a secret world (WARNING VERY HARD)

Answer 4

you beat level 2 and 5 with mini Mario