World 1 is a grassland world that is the first world of New Super Mario Bros. Wii.
World 1 consists of six regular levels, a Tower, a Castle, and Warp Cannon. The boss of the world is Larry Koopa. There are three Mushroom Houses, two of which are red and one is gold, as well as Princess Peach's Castle, where various video clips can be watched. The two red Toad Houses become accessible upon completing World 1-2 and 1-4 respectively, and the gold Toad House can be unlocked by completing World 1-3.
Levels[]
| Level | Unlocks | Preview | Description |
|---|---|---|---|
| 1-1 | World 1-2 | 
|
This is the very first level as well as a beginner level in general. Goombas and Koopa Troopas are encountered here as enemies. |
| 1-2 | World 1-3, Red Mushroom House | 
|
This is the first underground level, and it features Piranha Plants. |
| 1-3 | World 1-Tower, Gold Mushroom House, 1-Cannon | 
|
This is the first level in which Yoshi appears. It also features a secret exit. |
| 1-Cannon | World 5-1 | N/A | This is the Warp Cannon of World 1, and it takes the characters directly to World 5. It is unlocked by finding the secret exit of 1-3. |
| 1-Tower | World 1-4 |  |
This is the first tower level, and it features pillars capable of crushing Mario and the others. At the end of the tower is a boss fight against Larry Koopa. |
| 1-4 | Enemy Area, World 1-5, World 1-6, Red Mushroom House | 
|
This is the first underwater level, and it features Cheep-Cheeps, Deep-Cheeps, and Eep-Cheeps. |
| 1-5 | World 1-Castle | 
|
Takes place on a series of tall mushroom platforms. |
| 1-6 | World 1-Castle | 
|
A plains level featuring rolling hills. Koopa Troopas, Goombas, Piranha Plants, and Koopa Paratroopas are the enemies encountered here. |
| 1-Castle | World 2-1 , World 2-2 | 
|
This is the first castle level. It features several cogs as well as Thwomps. Larry Koopa is fought here as a boss again. The background music on the castle level is played by the pipe organ. |
