World 3 (Super Mario Bros.: The Lost Levels)

World 3 is the third world found in the Japanese version of Super Mario Bros. 2. It is also the first world in the game to have Hammer Bros. as enemies.

World 3-1
This is the first level in the game that Hammer Bros. appear. The player starts off next to the castle. When the player walks ahead, he'll encounter two Hammer Bros. taking residence on two long block platforms. On the bottom platform, the fifth block to the right has a Starman, but it's not required to beat the level. After jumping over a small hole, the player passed two koopa troopas. Above the koopa troopas, there is a ? block with a Mushroom/Fire Flower, but it too is not required to beat the level. Then the player jumped over a piranha plant and jumped up and over another platform. If the player chose to jump under the platform, they could climb a vine to get to a Coin Heaven. If the player chooses not to get to the coin heaven, the player will have to avoid three koopa paratroopas to get to three ? blocks, the farthest one

World 3-2
World 3-2 is an underwater level. The player starts floating down to the green blocks below, near a bloober. The player must avoid the oncoming bloobers and cheep cheeps while navigating tight holes obscured by corral and more green blocks. There are also 37 coins to collect, and three Koopa Troopas scattered throughout the level. These underwater koopas cannot be defeated unless the player has obtained a Fire Flower or Starman. At the end of the level, a pipe will lead the player to the overworld, where the flag can be found.

World 3-3
This level is apparently snowy, like the one in the original, and with Mario jumping above treetops. At the beginning of the level, a chance for a 1-up is available by knocking a green Paratroopa to the left and following it because of the shell hitting several enemies. The level also includes separate single and double blocks and pipes with Pirahna Plants in them, so it would not be wise to dash through the level recklessly.