World 5-5 (Super Mario Bros. 3)
From the Super Mario Wiki
Almost the entire level is made up of Donut Blocks. Mario starts on a Hard Block, with two Koopa Paratroopas and a Paragoomba nearby. Afterwards, there are some more Hard Blocks, one of them with a power-up inside, some Brick Blocks blocking Warp Pipes, and some ? Blocks, one also containing a power-up. These are guarded by another Koopa Paratroopa and two Fire Piranha Plants. Shortly after this, there are two rows of coins above and below a Donut Block bridge, along with a Flame Chomp. There are also some Fire Piranha Plants, as well as Hard Blocks and Brick Blocks, two containing power-ups. This is followed by a Paragoomba and some more Koopa Paratroopas; after this, the player reaches the goal.
By entering the second Warp Pipe at the beginning of the level, the player can find a bonus area with some coins and a Tanooki Suit.