World 1-6 (Super Mario Bros. 3)
From the Super Mario Wiki
This is another athletic level, featuring moving platforms set on tracks.
In the beginning of the level, the player must jump across gaps between tall platforms, while avoiding the Koopa Troopas on them. They will then encounter the first moving platform, followed by some Jump Blocks. After some flat ground are more tall platforms, suspended by wires. Below these platforms is an erratic track, with a Koopa Paratroopa found along its path. Past the track are more moving platforms, which will eventually lead the player to the goal.
There is a 1-Up Mushroom located in this level; in the area with flat ground are multiple Brick Blocks. There is a row of four of them in midair; the third one from the left contains the 1-Up Mushroom.