World 3-A (New Super Mario Bros.)

World 3-A is the first secret level of World 3 in New Super Mario Bros. The level is a coastal level, featuring Skeeters. This level is unlocked by paying five Star Coins at a Star Coin Sign at the beginning of World 3, allowing the player to play this level in favor of World 3-1.

Layout
This level starts with Mario jumping onto the barrels, while jumping on the Skeeter. After passing the Red Coin Ring, there are several moving platforms. Mario needs to jump on the last one while avoiding the Skeeter to jump onto the next platform. After that, Mario should hit the ! Switch to activate the red blocks for him to continue. To get the first Star Coin, Mario needs to either let the Skeeter use a bomb to destroy the blocks that block the Star Coin, or, more simply, go into the water, and go low enough so that the player can go under the blocks (off-screen) but not low enough to lose a life. To get the second Star Coin nearby, Mario needs to jump off the Koopa Troopa below the coin. After going through the Warp Pipe, Mario can get the third Star Coin by going into the next Warp Pipe and, as Mini Mario he should run on the water and jump to the Star Coin. After this, Mario should go past the moving platforms to the final Warp Pipe, reaching the Flagpole.

Star Coins

 * Star Coin 1 - After the checkpoint, there should be a lone Skeeter. The Star Coin is protected by brown blocks and requires the Skeeter's bombs to penetrate it, or the player can just swim directly under the blocks and then up to the coin.
 * Star Coin 2 - After the first Star Coin, the second Star Coin is in midair and requires Mario or Luigi to jump off a Koopa Troopa or Skeeter to get it. It can also be sometimes gotten by jumping from the barrels.
 * Star Coin 3 - After taking the Warp Pipe to the second area, the player should become Mini Mario or Luigi and take the regular Warp Pipe, not the small one. They should run across the water and jump to get the final Star Coin. The coin can also be obtained by using a Mega Mushroom.

Enemies

 * Skeeter
 * Koopa Troopa
 * Koopa Paratroopa
 * Micro Goomba
 * Cheep Cheep