World 4-A (New Super Mario Bros.)

World 4-A is the only secret level of World 4. It can be unlocked by spending five Star Coins.

Layout
This level has more Poison Water in it. To begin, Mario needs to swing on the vines in order to get to each platform. The player should soon see a paddle wheel, and then they should use it to again jump onto land. When Mario finds a Koopa Paratroopa in the way, he can jump on it to get a boost, which Mario must use to get the first Star Coin. This is also used to reach some faraway ledges. To get the second Star Coin, Mario should use a Koopa Paratroopa to bounce up to a vine above him. Mario should swing into the Warp Pipe to reach a cave with the Star Coin inside. The player should notice two green pipes and a yellow pipe together. Mario should enter the lowest one to get the third Star Coin, and after this, Mario reaches the Goal Pole.

Star Coins

 * Star Coin 1 - Near the middle of the level, the player needs to jump off the Koopa Paratroopa to get the Star Coin without falling into the Poison Water.
 * Star Coin 2 - The player needs to jump off a Koopa Paratroopa to reach a vine and then enter the nearby Warp Pipe. Mario must hit the P-Switch and defeat all the of the Koopa Troopas before getting the second Star Coin.
 * Star Coin 3 - The player needs to enter the lowest aforementioned pipe to collect the third Star Coin.

Enemies

 * Goomba
 * Koopa Troopa
 * Koopa Paratroopa
 * Piranha Plant