World 4 (New Super Mario Bros. Wii)

World 4 is the fourth world of in the game, New Super Mario Bros. Wii. It features several tropical islands, therefore, most of its levels are water-themed and make rather good use of the Penguin Suit, which can glide over water and allow Mario to swim better. Also, on the map is a bridge guarded by a Porcu-Puffer that can jump up and make Mario and the gang endure an Enemy Course. This is also the first world to have a level on an Airship, like the ones in Super Mario Bros. 3.

This level has two choices right from the start-platforms or water. The player can clear the level by jumping on platforms or only being in the water. This level has Urchins, Mega Urchins, Cheep-Cheeps, Spiny Cheep-Cheeps, and other enemies like those.

A lot of this course is filled with Donut Blocks and Cheep-Cheeps that will jump up to attack the player. To get one of the Star Coins, Mario has to stand on a long falling platform with the Donut Blocks' coloration.

This is the only level that features Huckit Crabs. There are also a lot of Urchins and Mega Urchins.

This tower features a lot of conveyor belts. Metallic blocks are also a common sight here; some must be jumped on to advance, while others are more of a nuisance. If the player isn't careful, he/she may get crushed by the blocks. Wendy O. Koopa is fought here, at the end.

When the player gets to the room where the metallic blocks form a staircase, they can run across and enter a wall with a darker coloration to find a secret pipe to the secret exit which unlocks the cannon to world 6.

This is an underwater level. It is infested with Bloopers, Blooper Nannies and pipes that blow bubbles. There is a secret area that where the player can get a Starman and another one where there is a Penguin Suit and the second Star Coin. The last one is inside a wall near the end of the underwater section. In one Bonus Area, one of only two Cheep Chomps in the game can be found.

In this level, at the start, the floor moves up or down when the player stands on it (right at the beginning there is a Starman too). Enemies found here include Boos and Little Mousers. A secret exit can be found at the bottom of one of the areas of floor, that takes the player to another part of the level. In this part, possesed furniture and a Big Boo can be found. This exit gives the player access to the castle and a Starman house. To get to the regular exit of the level, the player must break through some Brick Blocks to get to a door. Through this door is a long area of stairways going up and done, where many clusters of Little Mousers run along. This exit takes the player to

This level is on a beach filled with Lakitus and cloud blocks (when the player hits them, they turn into Lakitus that throw coins instead of Spinies). At the beginning, and in other places around the level, the player can find a Yoshi, to make the level a bit easier. Some areas can only be reached by riding a Lakitu's cloud.

This course features fences that can be held onto, along with some Climbing Koopas that cling onto the fences. The player can sometimes also change which side of the fences he/she can hang on from.

Additionally, the spiked pillars that appeared in Wendy's Castle and the Valley Fortress back in Super Mario World make an appearance here. However, the are all horizontal instead of vertical.

Fishbones make their first appearance in this game here.

The player faces Wendy O. Koopa for a second time here. However, at times the water level will rise, which can make it harder for the player to stomp on her head.

This is the first airship level in the game. The main enemies in this level are the Mecha-Koopas and the Rocket Engines. There is a pipe where Mario will find screws, which he must jump along to get a Star Coin. Near the end, there are Cannons and pipes that release Bob-ombs. The flames from the Rocket Engines can make them explode. The boss of the airship is Bowser Jr. in a Koopa Clown Car. The player must propel up with Propeller Blocks, or a Propeller Suit if the player is lucky enough to have one, and stomp on his head 3 times.

Enemies Introduced

 * Mega Urchins
 * Porcu-Puffers
 * Huckit Crabs
 * Bloopers
 * Baby Bloopers
 * Blooper Nannies
 * Cheep-Chomps
 * Little Mousers
 * Climbing Koopas
 * Fishbones
 * Spike Pillars
 * Mecha Koopas
 * Rocket Engines

Other Appearances
World 4 appears in Mario & Sonic at the London 2012 Olympic Games under the name "Cheep Cheep River" as the location of the Dream Rafting event. Porcu-Puffers, Thwomps, Cheep-Cheeps, and Bob-ombs appear in it, as well as the addition of Gooper Blooper.