From the Super Mario Wiki
This is an aerial level with many bouncy mushroom platforms and Lakitus. Mario begins on some colored blocks beside some ? Blocks. One of them contains a Super Leaf. Then, a bouncy mushroom platform, a bouncing Spiny and a set of orbiting Brick Block platforms can be found. This follows with another bouncy platform and another Spiny. Over a colored block, more bouncy mushrooms and Spinies can be found. A short rainbow-colored platform follows where a multi-Coin Block can be found. After a few more mushrooms and Spinies, a Lakitu appears. A Gold Ring can be found above one of the bouncy platforms, causing Lakitu to throw coins instead. Another set of orbiting Brick Block platforms can be found. This follows with the Checkpoint Flag. A Roulette Block can then be found, followed by some orbiting Brick Blocks and a Red Ring. Mario then crosses over several bouncy mushrooms on rainbow-colored elevated platforms. A Coin Roulette Block can be found along the way. Another set of orbiting Brick Blocks can be found, followed by the flagpole.