How do you get the tubes in New Super Mario Brothers?

Answer 1

Well in New Super Mario Bros. DS, when in World 3 in the last Castle, Grab a minimiser mushroom which makes Mario extremly small and complete the castle in that form, when you beat the boss, instead of going straight ahead, you will go down a small path underneath the normal path, this will lead you to World 4 instead of usually World 5, there is many of these types of secrets in the game, they just need a bit of thinking, I hope this answers your question.