Isn't that 11?
Dungeon thing
Snow
Cactus
Mushroom
Nether
Mineshaft
7.... (forgot this one)
Redstone stuff
End
Nether fort
Castle
If I forgot one (or can tell me what 7 was lol) please tell me
I'm having trouble here as well.
imtotallychris said you need to be super fast, but the one wall retracts too fast and even if you were somehow fast enough there's nowhere else to jump but back to where you jumped from.