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 Poisoned 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, jump on it to get a boost. Use this skill to get the first Star Coin. This is also used to reach some faraway ledges. To get the second Star Coin, use a Paratroopa to bounce up to a vine above him. Swing into the Warp Pipe to reach a cave with the Star Coin inside. The player should notice three pipes together (green, yellow, green). Enter the lowest one to get the third Star Coin, after this, Mario reaches the Flagpole.

Star Coins

 * Star Coin 1 - Near the middle of the level, the player needs to jump off the Paratroopa to get the Star Coin, but be sure not to fall into the water.
 * Star Coin 2 - The player needs to jump off a Paratroopa to reach a vine and then enter the nearby Warp Pipe. Hit the P-Switch and kill all the Koopas before getting the coin.
 * Star Coin 3 - The player needs to enter the lowest aformentioned pipe.

Enemies

 * Goomba
 * Koopa Troopa
 * Koopa Paratroopa
 * Piranha Plant