World 7-7 (New Super Mario Bros.)
From the Super Mario Wiki
This level mostly comprises of Donut Blocks and one-way platforms. There are several Red Koopa Troopas and Paratroopas. There are few solid ground areas through the level, and there are several item blocks. Beyond the first third of the level are many moving platforms. There are no secret areas in this level, therefore all the Star Coins are relatively easy to get. At the end of the level, a Red Koopa Paratroopa can be used to gain height on the flagpole.