World C (Super Mario Bros.: The Lost Levels)
World C is the fourth secret world that was first featured in the game Super Mario Bros.: The Lost Levels. After clearing this world, the player will gain access to the final world in the game, which is World D.
 World C-1
This night time, snowy overworld level mostly has Piranha Plants and Green Paratroopas. There's a warp pipe that leads to a staircase made of blocks with coins. There's also two Poison Mushroom on this stage so Mario and Luigi needs to watch out.
Note: The original version of this level isn't snowy, but still takes place at night.
 World C-2
This stage takes has no snow, unlike the first stage, and is mostly contains bridges and mushrooms-like platforms. There are dangers from above and below with jumping Cheep-Cheeps, Bloopers, and off screen Bullet Bills. This stage has only one ? Block and no Brick Blocks or Warp Pipes.
 World C-3
This stage has Mushroom-like Patforms and springs. The only enemies here are Lakitu (with Spinies) and both Red and Green Para-koopas. There is also a strong wind in this stage that blows against the player. This wind can blow the player right off the stage.
 World C-4
This level is exactly the same as World 7-4, except for that a few more Fire Bars have been added. The Koopa Troopas and Buzzy Beetles also move at a faster speed in the SNES remake. Another change is the addition of some blocks that appear near two sets of clockwise-moving Fire Bars. The blocks are obviously there to make it harder for Mario or Luigi to get past the Fire Bars unscathed. The False Bowser in this level is really a Buzzy Beetle in the original Famicom version, but in the SNES remake, it's a Bullet Bill who throws hammers, instead of spitting fireballs.