World 5-Castle (New Super Mario Bros.)
From the Super Mario Wiki, the Mario encyclopedia
This level has many conveyor belts that Mario must jump onto, some having Piranha Plants and Dry Bones on them. Along the way, Mario will find the first Star Coin. Later, Mario should see three conveyor belts with some Dry Bones moving along them, and even a springboard. He should jump on the moving springboard to get the second Star Coin. To get the last Star Coin, Mario should first notice that, after a Super Piranha Plant, there will be a block with a hole in the ceiling above it. Mario should run and jump to the block and then Wall Jump through the hole in the ceiling. When the player goes to the right, they will fall down. Go to the left to get the last Star Coin. After going through the double doors, Mario will find and face Petey Piranha. If Mario does not have a Fire Flower, he must wait for Petey to pound the ice and fall. Then, Mario must stomp on Petey three times to defeat him, thereby going to World 6. If Mini Mario beats Petey (by Ground Pounding him three times), he will go to World 7 instead.