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