A payment of five star coins is necessary to unlock this level.
This level takes place in a maze of pipes, full of alternative pathways and opportunities to get hundreds of coins. For the purpose of this guide, we will discuss the quickest way to complete the level first, followed by a guide for the star coins.
You start off atop a green pipe. To your right is a goomba and some blocks. These only possess coins, not power-ups. On the other side of the piranha plant, however, is a block floating above an abyss on the ground. Stomp on and grab the koopa nearby and throw it below to make a Mushroom or Fireflower come out. With your new power, continue onwards, jumping over the piranha plants' pipes. Eventually, you will come across a pipe pointing upwards. Duck in it to be shot up to a higher level, where you'll see the midpoint flag on your right.
After the flag, you'll see a piranha plant above two ? blocks. The one on the right contains a fireflower. Firther right are another two blocks. The one on the right flies away after being hit. Catching it again grants a 1-Up, but unless you can skillfully jump over several goombas and another piranha plant, it's not worth the aggravation. Take a running leap over the extra large piranha plant, and continue going right. You'll come across a maze of pipes below, with various folding platforms pushing you through. Just avoid the piranha plants when they emerge and you should come out fine.
Eventually, you will reach the ground again. Then, there will be stairs made of pipes to the right. Carefully climb these stairs, avoiding the parakoopa and piranha plant. If you jump up to the pipe above and to the left, you can hit a hidden block to get a 1-Up. Finally, at the top of the stairs, wait for the piranha plants ahead to fall into their pipes and jump over to the flagpole.
Star Coins[edit]
As a bigger version of Mario, buttstomp the breakable blocs on the ground near the beginning of the level. You will fall into a new area containing the first star coin. Then, take the path to the right to where a pipe is. Dive into it to be shot up back to the main level.
The second star coin is later in the level, in the final maze of pipes. You should see it your first time going through the level, but have to be careful to grab it. Fall down and go a little bit left to reset the falling platform, but stay far enough to the right to avoid being trapped. Grabbing the star coin is simple enough so long as you take a second to think things through.
The third star coin is near the very end of the level. While standing at the bottom of the group of four pipes with piranha plants, on the other side of the stairs, jump up between the pipe sticking to the left and right. A block will appear, allowing you to go into the pipe to the left. Inside is a giant piranha plant and a red koopa. Use the koopa to take out the plant and grab the star coin its guarding.