World 4 (Super Mario Bros.: The Lost Levels)

World 4 is the fourth normal world that is featured in the game Super Mario Bros.: The Lost Levels, following World 3. After the player has beaten this world, he or she will have access to World 5. It is also the first world to introduce the red Piranha Plants, replacing the green Piranha Plants from the first three worlds.

World 4-1
The player starts off outside, and finds two red Piranha Plants along with a Lakitu. The player finds a gap in between a line of Brick Blocks. The block that the player can hit with a normal jump contains ten coins. The player then encounters another red Piranha Plant, and after the player passes this pipe, Lakitu floats away from the screen. The player finds seven ? Blocks, the last one containing a power-up, and the rest containing coins. The player then finds a Trampoline, and water which the player cannot swim in. The player needs to jump over the water using the Trampoline. Another Lakitu chases after the player. Soon, the player finds three ? Blocks, two containing coins while the other contains a Poison Mushroom, along with a pipe with a red Piranha Plant inside of it. The player encounters two ? Blocks, one of them with a coin, and one with a power up, while seeing pipes on top of a row of ? Blocks containing coins. The first pipe along the row of Blocks is an underwater shortcut that just takes the player to the first pipe he or she finds on the bottom. The shortcut has Bloopers, and Buzzy Beetles, along with coins scattered around the place. A ? Block with a coin can be seen here, along with a Brick Block containing a Vine which leads to Coin Heaven, however, he or she then goes back to the place where the player couldn't swim in the water. The player must see some more red Piranha Plants, and a staircase with a Goomba, along with the Flagpole. He or she now gains access to World 4-2.

World 4-2
After a couple of steps, the player can see a Bill Blasters surrounding a lone ? Block containing a power-up. Then, the player finds a Brick Block containing a Star, a couple of Buzzy Beetles, and two ? Blocks with coins. Now, the player finds a Trampoline, and two rows of Brick Blocks with a Koopa Troopa on the top one, along with Lakitu's appearance again. If the player kicks the Koopa Troopa and runs along with it, it defeats Goombas and Koopa Troopas, eventually giving the player an 1-Up. The Lakitu now disappears. The player soon finds more Bill Blasters, and a lone Koopa Troopa, along with nine ? Blocks. The one above the first Bill Blaster contains a power-up, while the other ones have coins. The player encounters another Koopa Troopa, and a Brick Block hanging right under a pit which contains ten coins. The player finds a Hammer Bro., and then has the option of going up or down. If the player chooses to go up, he or she fights another Hammer Bro., however if he or she chooses to go down, they find two red Piranha Plants and seven ? Blocks containing coins. The player finds another red Piranha Plant, and some blocks the player can jump on top of. There is a Koopa Paratroopa here, and the Flagpole. The player must slide down it to open up World 4-3.

World 4-3
The player starts off at a platform. He or she must make a big jump to another platform with a Trampoline, and a steady platform, along with a moving one. Then, the player finds two platforms that are connected together, and falls if he or she is standing on them. Then comes another moving platform and Koopa Paratroopa. The player has to make another huge jump, except this time, the player must bounce off the Koopa Paratroopa so that he or she makes it to the platform which has coins on it. The player then finds another trampoline, along with coins and another moving platform. A lone ? Block under the moving platform contains a power-up. After the player makes it to the next set of platforms, and jumps on top of the falling one, Bullet Bills starts to come after the player. The player finds another set of platforms connected by a rope, and they can either jump to the platform which contains coins, or the platform which has a Koopa Troopa, along with a big gap the player has to jump from. If the player takes the top route, he or she can use the falling platform and jump off it to the next platform, while collecting coins in the air. The player encounters two more Koopa Paratroopas, and two floating blocks in the air. The player can then see the Flagpole from here. Players must slide on it to go to World 4-4, the final level in World 4.

World 4-4
Starting off, the player finds a Koopa Troopa walking on seven ? Blocks, and a huge firebar. Six of the Blocks contain coins, while the one next to the firebar contains a power-up. The player encounters a regular firebar, along with three Goombas. Another huge firebar is seen here, the player has to jump on top of the stone blocks the firebar is anchored on, and a regular firebar can be seen below, along with a moving platform that goes vertically. The player advances, and finds a firebar, along with three Koopa Troopas. He or she then sees a falling platform, which safely takes the player to the ground on the right of it. A firebar and a Hammer Bro. can be seen here. Then, the player finds a red Piranha Plant, two firebars, and three Goombas. The False Bowser in this level starts to shoot fireballs at the player. If the player chose to go through the middle route of the firebars, he or she finds a Hidden Block, which contains a power-up, and another one beside it, which contains a coin. Also, if he or she chooses to go underneath that one, another Hidden Block with a coin can be found. A red Piranha Plant and a moving platform can be found here. The player must then jump to the Stone Block. A Podoboo along with a firebar with a False Bowser can be seen. The player must defeat the False Bowser here, and rescue four Mushroom Retainers, advancing to World 5.