World 3 (New Super Mario Bros. Wii)

World 3 of New Super Mario Bros. Wii is an ice-themed world conquered by Lemmy Koopa. The Penguin Suit is introduced in this world. This is also the first world in the game that has a switch that can change the obstacles slightly in levels, similar to Switch Palaces. On the map is an area with ice that has two Ice Bros. on it. If Mario and the gang are hit by them, they will endure a battle game where they will have to complete the Enemy Course.

World 3 Ghost House
This is the first Ghost House in the game, Big Boos, little boos, and possessed furniture are the main obstacles in this level.

World 3 Castle
Lemmy's Castle is riddled with giant falling icicles and frozen floors making timed jumps difficult, there is also a segment with bottomless cliffs which are traversed by a frozen moving raft similar to the ones seen in Roy and Larry's castles in Super Mario World.