World 1 is the first world in New Super Mario Bros. Wii. It is a sunny place with clouds and mushrooms in the background. This is where Peach's Castle is. Every now and then, you must go to the castle to buy and watch movies. This is the first world to allow you to use the Propeller Suit. Yoshi's appear in World 1-3. The first sky level is World 1-5. Like all other worlds, World 1 has 7 levels including the Enemy Course and 3 Mushroom Houses. One is a castle and one is a fortress. Larry Koopa is fought twice here. One you defeated him, the second time, you can move on to World 2. 3 Mushrooms Houses are here. One is a Yellow Mushroom House. The other two are Red Mushroom Houses. If you took Toad to the goal in a level, a Mushroom House will appear on the arrow plate next to Peach's Castle. The cannon is difficult to understand how to unlock. However find secret pathways. That means go through pipes, and other places to find out how.