World 1-2 (New Super Mario Bros. Wii)
World 1-2 is the second level of World 1 in New Super Mario Bros. Wii and the first underground level of the game. The level is full of shifting crystals and introduces the player to the Tilt Lift. It is unlocked by completing World 1-1 and its own completion unlocks World 1-3 and a Red Toad House. Except at the very beginning and end, the Underground Theme plays through this level.
Most of this level takes place underground. At the beginning of the level, players must avoid Goombas and run through a wall to a hidden Warp Pipe which leads to the underground area. There are many tilting platforms made of crystal seen throughout the cavern, the first set of which leads up to a POW Block. Past this is a couple of pipes with a Koopa Troopa and a few Piranha Plants; between them are dozens of coins and Brick Blocks. Afterwards is the midway point. Players can jump down into the space below the ground to grab a Super Star which can be used to defeat several enemies ahead. Above the pipe leading to the third Star Coin, a group of Brick Blocks is found. After the player destroys all the Brick Blocks, they can Wall Jump upward to a secret area to collect extra coins. Past this area is another Tilt Lift with a Red Ring and another Warp Pipe that leads outside. A Tilt Lift can be used to reach the top of the flagpole.