World 1-1 is the third level of Grass Land in Super Mario Bros. 3 and its remakes Super Mario All-Stars and Super Mario Advance 4: Super Mario Bros. 3. The player is given a time limit of 300 seconds to complete it.
This is a basic overworld course similar in appearance to World 1-1. The player stars along a stretch of land, where they will first encounter a Boomerang Brother. Up ahead is a large formation of Brick Blocks, featuring two Jump Blocks on the left, two ? Blocks on the inside, and a red Koopa Troopa strolling back and forth on the top right. One of the blocks below the Koopa is a 10-Coin Block.
The Koopa's shell can be used to break through many of the blocks, allowing the player to reveal a block containing a power-up, as well as a secret Jump Block that can lead the player to Coin Heaven, where the player can collect a total of 61 coins, some of which are placed high above around a Brick Block containing a 1-Up Mushroom. The player will need to make use of the character's Raccoon form to reach them, though the P-Wing power-up would be more useful. Upon exiting the Coin Heaven, the player will be dropped near the end of the level.
Back on the normal path, following the Brick Block formation is a horizontal row of wooden blocks, followed by four appearances of vertical wooden blocks pillars. The top block on the second pillar contains a power-up. Goombas stroll in between these pillars, and two sets of three coins are placed high above the space between the last two pillars. Another Boomerang Brother awaits on the short stretch of land ahead. On the final stretch of land, not far from the goal, are seven block platforms, where enemies such as Goombas and a Para-Goomba are encountered. This is also the area the player will land in after exiting Coin Heaven. A few coins appear here, plus out of the seven platform, one of them is a white platform.
By holding down on the directional button pad for a moment, the player can drop behind the scenery allowing them to run behind the darkness of the goal area. The player must be quick and rush to the end, as they will not remain behind the scenery for long. If successful, the player will still complete the level as usual, but will also unlock access to a hidden Toad House, which contains a Magic Whistle.