World 2-A (New Super Mario Bros.)
World 2-A is a secret level in World 2 of New Super Mario Bros.. It is the only secret level in this world, and has two exits; the normal exit opens a pipe that leads to the world's castle, and the secret exit opens up the world's Warp Cannon.
The level takes place over a stretch of water. The level features Koopa Troopas, Koopa Paratroopas, and Spike Basses. The player must traverse across many platforms and utilize several Spin Blocks to proceed through the level. By using the Spin Blocks, the player can gain access to many coins that hover in the sky. The flagpole for the normal exit is accessed via the use of a green pipe near the end of the stage, located directly below a yellow one.
To access the secret exit, the player must reach a platform containing a yellow Warp Pipe near the last Spin Block, which is most easily done by using the Spin Block and then bouncing off the nearby Koopa Troopa. Entering the pipe will lead to the third Star Coin and another pipe that will take Mario to the secret exit.