World 6-6 is the sixth normal level of World 6 in New Super Mario Bros.. Completion of this level unlocks World 6-Castle.
This level is the only one in the entire game that contains Chain Chomps. First, the player must jump on the Spin Blocks, and fly through the air, avoiding the Chomps along the way. If the player goes as high as they can on the platforms and goes left, the player can collect a Star Coin located on a Chain Chomp's post. After the Star Coin, they must continue left and slide down, leading to an area with another Star Coin with blocks covering the way to it. The player must use the Spin Block, get above a stack of Blocks, and use the Drill Spin, which reveals a P Switch. Activating it allows the player access to the Star Coin, and a few bonus Coins. After the midway point, the player can enter a Red Ring, which only works if they slowly spin down to it. To get the final Star Coin, the player must first destroy any blocks that block the Spin Blocks. Then, with perfect timing, they must spin onto the Koopa Paratroopa directly below another P Switch. After pressing it, they must hit the next Koopa in sight and bounce off of it into a nearby Warp Pipe. Here, they must slide down and Wall Jump to the Star Coin. In the final area, the player can enter several green Warp Pipes, being blasted higher each time. Lastly, when the player reaches a set of four pipes, they can enter the third pipe to reach the top of the pole.
- Star Coin 1: This coin is located slightly below the top-left corner of the level, and is obstructed by bricks. The player can use the nearby Spin Block to drill through a set of blocks and hit a P Switch, opening up the way to the coin.
- Star Coin 2: Near the top-left of the level, sitting atop a Chain Chomp's post.
- Star Coin 3: Shortly after the midpoint, there is a Warp Pipe that the player can enter, but bricks block the path to it. To enter the Warp Pipe, the player must ground-pound a column of bricks nearby, use the Spin Block, then glide to the right, bouncing off a Koopa Paratroopa to hit a P Switch, then bounce off another one to enter the pipe. Once inside the bonus room, they must use the Spin Block to glide up and then slide down the left pipe to obtain the Star Coin. Alternatively, the player can use the aforementioned Spin Block to glide to the right and bounce off of the Koopa Troopa, breaking the blocks to clear the way to the pipe.