World 5-1 (New Super Mario Bros. Wii)

World 5-1 is the first level in World 5 in New Super Mario Bros. Wii. It introduces the Stalking Piranha Plant and the River Piranha Plant. There are large Koopa Shells throughout the level. While most of this level takes place on land, a portion of it is over a body of water. There are many swinging vines that the player can use to travel over gaps and Stalking Piranha Plants. Completing this level unlocks the world's first Enemy Course and the levels World 5-2 and World 5-3.

Layout
The level starts out with a section full of Stalking Piranha Plants, which can be defeated with a Fire or Ice Flower. Next comes a portion where several bodies of water separate some parts of the land, filled with River Piranha Plants and Cheep Cheeps. After having traversed this section of the level, the player is presented to the midway point, with a few ? Blocks and Koopa Troopas. Next is a segment consisting of swinging vines hanging above some platforms, where some Stalking Piranha Plants are found walking around. Mario can choose to either swing his way into the next part, or fight the enemies on the ground. After that sits another body of water over which a paddle wheel can be ridden to reach the next area, as the cliffs are too high to get to just by jumping out of the water, and River Piranha Plants are found in the water. Then, a few more Stalking Piranha Plants come, before a swinging vine can be seen and used to go inside an oversized Koopa Shell to access the room where the third Star Coin is located. If not, the player simply goes inside a Warp Pipe beneath to make it to the end of the level.

Star Coins

 * Star Coin 1: At least a Super Mushroom is required for this one. To the left of the first giant Green Shell, there is a hidden area in the ground that is blocked off by bricks. After Ground Pounding through them, Mario and co. should run under the Green Shell and can see the first Star Coin floating right under it.
 * Star Coin 2: Similar to the first Star Coin, the second Star Coin is floating right under the second giant Green Shell. Mario and co. must swim inside it, then jump up to the Star Coin.
 * Star Coin 3: Near the end of the level, instead of taking the usual exit Warp Pipe, Mario and co. should use the vine to swing into the third big Green Shell and will see a hidden green pipe inside. After going in the pipe, Mario and co. should grab the POW Block to kill all enemies and make the third Star Coin attainable.