World 3 (New Super Mario Bros. Wii)

World 3 (New Super Mario Bros. Wii) is the name of an ice-themed world conquered by Lemmy Koopa in New Super Mario Bros. Wii. The Penguin Suit is introduced in this world. This is also the first and only 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.

3-1
This area is infested with Cooligans. The first part is simple, but the second part is a little more complicated. The later parts in this level are mostly designed to show the player how to make proper use of the Penguin Suits sliding abilities.

3-2
This level is a snow level that is infested with Bullet Bills. Ice Bros. appear at the end of the level.

Enemy Course

 * Two Ice Bros.
 * Three Ice Bros.
 * Four Ice Bros.

The Ice Bros. will throw ice balls that will freeze and damage Mario and crew. To quickly escape an ice entrapment, the player should simply shake the Wii remote or try to hit them from below.

3-3
This level is an icy cave level with 3 parts there are floating platforms, falling icicles, and giant falling icicles that Mario can walk on, and some enemies such as Swoopers.

3-Ghost House
This is the first Ghost House in the game, Big Boos, smaller Boos, and possessed furniture are the main obstacles in this level. There is a platform that goes down in an area infested with Boos near the end of the level.

3-Fortress
The last half of this level resembles Castle Crush, a level found in Donkey Kong Country 2: Diddy's Kong Quest. This level features brightly colored rotating blocks that must be used to climb to higher locations. Rolling spike balls, Dry Bones, and Amps are some of the hazards that must be avoided as the floor scrolls upward.

3-4
When the player first plays this level, he/she can only get to the secret red flag that takes him to 3-5. After hitting the Red Switch, all the red blocks will appear, letting the player beat the level the regular way. Moving ice blocks and Fire Bros. do make an appearance here.

3-5
When the player plays this level the first time, he/she can only reach 1 of the 2 endings. However, if he/she returns after hitting the Red Switch, red blocks will appear, and he/she can reach the hidden goal, unlocking a yellow Starman house.

3-Castle
Lemmy's Castle is riddled with giant falling icicles and frozen floors making timed jumps difficult. There are also some segments with bottomless cliffs, which are traversed by a moving raft similar to the ones seen in Roy Koopa and Larry Koopa's castles in Super Mario World. However, this one is frozen. This is also the first level to feature Bob-ombs.

Lemmy Koopa is fought again here. As he takes damage, Lemmy's ball will grow bigger in size after he is done sliding his shell to attack Mario and gang.

Enemies Introduced

 * Cooligans
 * Bullet Bills
 * Bill Blasters
 * Boos
 * Big Boos
 * Amps
 * Swoopers
 * Ice Bros.
 * Bob-ombs