From the Super Mario Wiki
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The player starts facing two charging Hammer Bros. on two row of Brick Blocks, the top second-from-the-left of which contains a power-up. To cross the gap ahead, the player has to time a jump off of a Koopa Paratroopa or jump off from the top row of Brick Blocks. After the Bill Blaster at the top of a flight of stairs are some Brick Blocks, the third of which holds a Poison Mushroom, but above it and slightly to the right is a Hidden Block with a 1-Up Mushroom. Through a Warp Pipe on a row of ? Blocks is an underground chamber with a power-up, a Poison Mushroom, and some Coins. In the next row of Brick Blocks up high, there is a Super Star in the second-from-the-right block, and in the Brick Block above the next pipe is a Poison Mushroom, followed by the exit pipe from the earlier underground chamber. In the Brick Block above the pool of water is a power-up, and to cross the pool of water, the player has to time a jump off of a Koopa Paratroopa. Immediately after the pool of water is a flight of stairs with a Bill Blaster at the top, followed by two charging Hammer Bros. After a group of pipes with wind blowing between them and narrow blocks is the Goal Pole.