World 3-3 (New Super Mario Bros. Wii)
From the Super Mario Wiki
World 3-3 is the third level of World 3 in New Super Mario Bros. Wii. It is unlocked by completing World 3-2. This level mostly takes place in an icy cave. Completing this course is not required in order to progress in the game, but doing so unlocks a green Toad House.
The level starts out on the snowy surface, with a ? Block and an Ice Bro located nearby. There is a Warp Pipe near the Ice Bro, along with a Hidden Block containing a 1-Up Mushroom. The pipe leads to an icy underground area with water, several falling icicles and moving ice blocks. After a Goomba-spawning pipe and the first Star Coin is a Roulette Block, an Ice Bro and more Goombas followed by a Warp Pipe leading to the midway point. The player then comes across giant falling icicles which can be walked across, along with more smaller falling icicles. After some distance, a giant falling icicle appears with another Warp Pipe nearby. Entering the pipe brings all players to another underground area. This section is filled with falling icicles. A barrel is found at the beginning of the area, under a platform next to a ? Block. After another Ice Bro is a Warp Pipe leading back to the surface. A small hill leads to the flagpole.