World 6 (New Super Mario Bros.)
World 6 is a world in the game New Super Mario Bros. This world is made up of rocky canyons and mountain-like terrain. This world introduces new enemies such as Fire Bars, and is the only world in the entire game to feature Chain Chomps. This is the only world apart from World 8 to have two Towers.
The boss of this world is Monty Tank.
 World 6-1
This level is filled with Bullet Bills. When Mario reaches a thin floor, he can either hang onto it or walk on it. When Mario is on the thin floor, it is hard for him to jump. If Mario Wall Jumps on the wall after the thin floor, he will get the first Star Coin. After the checkpoint, Mario should jump to the left to get the second Star Coin. Below another thin floor, after many Bullet Bills, is the final Star Coin. After the third Star Coin, Mario will reach the Flagpole.
 World 6-A
Lakitus will be chasing Mario in this level. There are also Tweesters in this level. The first one allows Mario to obtain the first Star Coin. Later, Mario should be met with two Lakitus at once. The player should see a part of the quicksand that is higher then the rest. If Mario goes into it, it will take him to an area containing the second Star Coin. After the checkpoint, Mario should find an area with several pipes. Mario should enter the single yellow one to go to an area with the third Star Coin (and a Super Piranha Plant). When he exits out of a red pipe, he should enter the green one next to it. After exiting a Warp Pipe, Mario will reach the Flagpole.
 World 6-2
This level has water that can rise. After the Red Warp Pipe, the player should see a ? block with two coins above it. In between those coins are two invisible blocks, one containing a Beanstalk. Climb it and press a P-Switch, jumping across some flying blocks to get the first Star Coin. Soon after that, Mario should reach two tall cannons. One takes Mario to a bonus area, and one takes you to the second Star Coin. Mario can get the last Star Coin by going past a few Spinies. When Mario goes through the yellow Warp Pipe, he will reach the Flagpole. This stage is similar to Mondo from Super Mario World.
 World 6-Tower
In this level, the Spiked Pillars return. Mario must jump before the spikes can damage him. Mario can get the first Star Coin by ducking to avoid a Spiked Pillar and by jumping to it. After the checkpoint, Mario must quickly jump up to avoid the Spiked Pillars below him. After the door is another area similar to the previous one. Mario should get to the top before getting the second Star Coin. To get the last Star Coin, the player must time their wall jumps very well or be Mini Mario. Mario must Wall Jump to a Green Warp Pipe. Enter it and avoid the four Spiked Pillars to get the last Star Coin. This time, Mario is able to jump on Bowser Jr.. This fight takes place on a tilting platform.
 World 6-3
This level has many pipes in it. To begin, Mario should hit a block with a string attached to it, so he can jump on it to get the first Star Coin. The player should then enter a red Warp Pipe, entering an area with purple goop. If Mario stands on the logs too long, then they will start rolling, causing Mario to fall into the goop. There is also an easy Red Coin Ring in this area. After exiting the area, Mario should enter the second green pipe from where he is standing to obtain the second Star Coin. Next, Mario should enter the pipe to the far right. This area contains many Piranha Plants. Mario can get the third Star Coin by finding a Moneybag, following it until it's on the pipe the player just exited, jumping on top of it, and moving left to get the coin. Wall Jump to escape the area. Soon, Mario will get to the Flagpole.
 World 6-4
This level has Firebars throughout the level. When the first Firebar appears, Mario should Wall Jump above it to get the first Star Coin. Mario should then come across the thin floors with his back against the wall. To avoid most of the Firebars, Mario should stay down, below the thin floor. Later, Mario must press a ! Switch to create two blocks that let him advance. After the checkpoint, Mario should go left to get the second Star Coin. After the red pipe, the player will be in an area filled with thin floors. Because Mario's jumping is limited, he should only jump when he is close to a moving platform. When the path splits, the player should take the upper path to reach the final Star Coin. After the Warp Pipe, Mario will reach the Flagpole.
 World 6-Tower 2
This level has conveyor belts with spikes on the ends of them. One third into the game, Mario can get the first Star Coin by simply jumping over spikes. The player should continue moving up, past the Dry Bones and more spikes, until they find two pipes. The right pipe will let Mario continue his way to the top. To obtain the second Star Coin, Mario should fall back down to an area filled with Spike Tops. He should then duck onto the conveyor belt and hit the blocks above him, ontaining the coin. Mario should climb a rope to get to the third Star Coin, and then he should go up and enter the double doors to face Bowser Jr. This time, Bowser Jr. will use the turtle shell technique, so Mario can't jump on him.
 World 6-5
When Mario enters the Warp Pipe, he will be underwater. The player should continue moving to avoid the Deep-Cheeps that home in on Mario, or otherwise hit them with a Fireball. The first Star Coin can be found near a Red Coin Ring. Then, there are Whirlpools that can suck Mario in, causing the player to lose a life. The player must wait until the whirlpools shrink to get by them. The second Star Coin is located in a yellow pipe in between some whirlpools. When the player finds a whirlpool with blocks on the bottom of it, Mario should let himself get sucked into it, being taken into an area with the third Star Coin. After some Mega Deep-Cheeps and a Warp Pipe, Mario will reach the Flagpole.
 World 6-B
To start, Mario must enter the Warp Pipe on the far right, blasting him to the top of the icy platform. Next, the player needs to grab several Ropes, some moving, and swing to the next few platforms. At the first Star Coin, Mario must grab a Shell, throwing it at the coin. Soon after that, the player should be at an area with tipping purple mushrooms. When Mario blasts out of the next Warp Pipe, he should jump bounce off the Paratroopa to get the second Star Coin. The next area contains Piranha Plants and more purple mushrooms. The player should later see three Warp Pipes, which all blast Mario to the same area, but at a different angle. When the player sees more ropes, they must swing to the top platform and run and duck to reach the last Star Coin (Unless they are Small Mario). Lastly, the player must make several tricky jumps across the pipes to reach the Flagpole (Unless they are Small or Shell Mario).
 World 6-6
This level is the only one in the entire game that contains Chain Chomps. First, Mario must jump on the Spin Blocks, and fly through the air, avoiding the Chomps along the way. If Mario goes as high as he can on the platforms and goes left, the player should see a Chomp with a Star Coin on the post. After the Star Coin, Mario should continue left and slide down, leading to an area with another Star Coin with blocks covering the way to it. Mario must use the Spin Block, get above a stack of Blocks, and use the Drill Spin, which reveals a P-Block. Activating it will allow Mario access to the Star Coin, and a few bonus Coins. After the checkpoint, Mario should soon see a Red Coin Ring, which only works if you 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, Mario must spin onto the Paratroopa directly below another P-Switch. After pressing it, Mario should hit the next Koopa he sees, and bounce of it, into a green pipe. Here, Mario can slide down and Wall-Jump to the Star Coin. In the final area, Mario should enter several green pipes, being blasted higher each time. Lastly, when the player reaches a set of four pipes, they should enter the third pipe, allowing Mario to reach the top of the Flagpole, earning him a 1-UP.
 World 6-Castle
To start, Mario should jump on the stone platforms as they pop out of the walls, avoiding the lava. The first Star Coin can be obtained by throwing a Shell at it. The second Star Coin is found halfway into the stage, on a moving stone platform. After dodging some fireballs, the player will reach the Checkpoint. Mario should Wall Jump to the top set of platform. Then, the player should see a Koopa and two stone walls to the right. If Mario runs and jumps off the Koopa, and goes right at the moment the wall is at its lowest point, Mario should be able to go over the wall. Mario should go right to reach the last Star Coin. After going through a door, the player should time their jumps correctly, in order to reach the double doors. Past this is World 6's Boss, Monty Tank. The battle takes place outside the castle. To defeat him, Mario must jump on his head three times whenever he comes out of the tank. Each time he is hit, however, another cannon will appear on the tank. After beating Monty Tank, Mario is able to go to the final World, World 8.
 Enemies introduced