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.

Layout
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 bricks. Afterwards is the midway point. Players can jump down into the space below the ground to grab a Star, which can be used to defeat several enemies ahead. Above the pipe leading to the third Star Coin, a group of bricks is found. After the player destroys all the bricks, 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 pole.

Star Coins

 * Star Coin 1: Right after the player enters the first green Warp Pipe, the first Star Coin is floating in a small alcove in the ceiling. It can be easily jumped to.
 * Star Coin 2: To the high right of the first Tilt Lift is a green Warp Pipe. After entering it, Mario and co. should activate the P Switch that is hidden in the lone brick. This turns the nearby coins into bricks, and Mario and co. must use them to reach the second Star Coin, which is floating high in the air.
 * Star Coin 3: At least a Super Mushroom is required for this one. The third Star Coin can be seen floating below the ground, surrounded by two red Warp Pipes. To the left of this is a green Warp Pipe with several bricks covering it. Mario and co. must ground-pound through the bricks to enter the pipe, and once in the area, Mario and co. should activate the POW Block to make the Star Coin fall to the ground.

Trivia

 * This level is the only level with 4 star coins, including the uncollectable third star coin.