Third Course (Impossible Pack)
From the Super Mario Wiki
Nearly the entire level features poison below that raises and lowers every so often. The level begins with an area consisting of several Note Blocks and Burners. This is followed by more Note Blocks with Grinders and several Dry Bones on some of the blocks. After the Checkpoint Flag is a Conveyor Belt moving opposite the player, with a pair of Burners and some Dry Bones. Another Conveyor Belt follows this, with a Big Bone Piranha Plant on it. Before the Warp Pipe leading to the end of the level, there are several Fire Bros standing on platforms with spikes, where Mario must make use of some Springboards to progress. The Goal Pole immediately follows.