World 4-3 (Super Mario Bros. 3)
From the Super Mario Wiki, the Mario encyclopedia
The area the player starts in is a long plain with two Sledge Brothers, and some large Brick Blocks separating the two. At the end of the plain is a Warp Pipe that will take the player into an underground cavern. Here, the player will encounter Buzzy Beetles and Spinies walking along both the ground and ceilings, and the platforms in the cavern are separated by large chasms, some of which have Koopa Paratroopas that can be used to help the player get across. After the ? Block with the power-up in it is a high platform with some coins the player can reach if they fly up using a Super Leaf. Afterward is a narrow passage with Buzzy Beetles and Spinies, and a 1-Up Mushroom can be found in the Brick Block at the far-left at the start of the passage, which will move along the path above. Next are small, sloped, floating platforms, the second of which has a small pillar of Wood Blocks that will knock the player back if they are touched. Going through the Warp Pipe at the end will take the player to the goal.