New Super Mario Bros./World 7-A

In the middle of the sky, one can find an odd building rising from the clouds. Enter it and you will find yourself inside the pipe maze, a complicated labyrinth of warp pipes that transport you between areas. Don't get lost as you navigate this confusing maze, as some pipes take you to hidden areas while others send you backwards! Also in this level are Squigglers, small Wigglers that can crawl on walls and ceilings.

Level walkthrough
Go into the pipe to get inside the pipe maze. Near the entrance, there is a pipe that spawns Squigglers. These miniature versions of Wigglers can be defeated through conventional attacks like stomping or fireballs, but they can crawl along the wall and ceiling. Run below the red platform to the end, then jump in the space between the platform and the pipe to the right to bridge the gap with hidden blocks. Get on the red platform and go into the warp pipe to the right to reach a chamber with the first Star Coin. Exit the chamber the way you came.

Jump into the pipe the Squigglers are spawning from to go up a level. You can go up the pipe to the left for a power-up, but you'd want to go right to progress. Get to the right wall, being careful of the Piranha Plant near it, then enter the pipe at the right wall. You will be launched up, collecting some coins on your way. Cling to the wall to your right and slide down until a warp pipe entrance to your upper-left is within reach. Jump into it to be teleported to a hidden area with the second Star Coin. Again, go back into the pipe to return to the maze.

Jump on to the blue platform and head into the pipe entrance on the left, taking you to the next level. Here, you can jump between the dark blue and red blocks to hit hidden blocks, forming a continuous path across. Jump from the red platform to the yellow platform above, passing the checkpoint in the process. You can knock the red Koopa on this platform into its shell, then throw it to the left on the red platform to hit a block containing a 1-Up. After that, jump on to some steps made of warp pipes. Watch out for the Piranha Plant, then go into the pipe above it to rise up to the next tier.

Now, head right along the pipe floor until you see a lone block. It contains a Mini Mushroom, a power-up that is certainly useful for this stage. Go left back to the pipe you used to reach this area, then wall jump up between the gap of the pipes. At the top of the gap is a mini warp pipe, which takes you to a secret area with the last Star Coin. Exit through the pipe on the right. Watch out for the Piranha Plants as you jump over the plant on the right. Enter the warp pipe in the wall with help from the platforms to exit the maze, leaving you at the flagpole area.

Star Coins

 * 1) Through a horizontal pipe at the very bottom of the maze is the Star Coin. Jump to the right of the red block platform to reveal hidden blocks to the pipe entrance.
 * 2) Look for a cannon pipe at the right wall on the second level of the pipe maze. After launching yourself up, cling to the wall on the right and jump to the warp pipe entrance when you pass below it to reach a room with the Star Coin.
 * 3) On the same level as the block where you got the Mini Mushroom, go left and wall jump up the thin gap between the two pipes to enter a mini warp pipe, which takes you to a secluded area with the Star Coin.