World 1-3 (Super Mario Bros. 3)

World 1-3 is the third level of Grass Land in Super Mario Bros. 3 and the third overall in the game. This level is plain-based and features Note Blocks and Boomerang Brothers. There are two secrets hidden in the level. The first one is accessed by using a red Koopa Troopa to destroy blocks, revealing a space where a secret Note Block can be accessed. The shell must be launched towards the left side of the screen to destroy the correct Brick Blocks. Jumping on this Note Block takes Mario to Coin Heaven.

The second secret is the Warp Whistle, which is found in a Toad House behind the goal. When standing on the white block with a red Koopa Troopa on it, Mario can slip behind the background by standing where the coin is and pressing down on the directional pad. Then Mario can run behind the black scenery to reach the Toad House.