Boo's Boneyard Galaxy: Racing the Spooky Speedster

Head down the pipe on the skull planet, then slide down the ramp to a Boo Power-Up. Now as Boo Mario, turn invisible to go through the wall on the right and speak with Big Boo.

Big Boo will challenge you to a race through this dank cavern. He always crosses the finish line at 53 seconds, so you'll have to move fast. Thankfully, you can trigger strategically placed fans, by grabbing their respective ? Coins, to speed through portions of the track. Furthermore, you can use Boo Mario's invisibility power to go through some walls for shortcuts.

Float along the path until you reach the first blue wall in the vertical shaft. Turn invisible to float through, then go through a second wall and grab the ? coin immediately after. This will activate the fan above, which will blow you down the shaft at high speed.

As you exit the shaft, hang right and grab the next ? Coin to activate another fan - ride its current to the area below. Watch out for the springs along the way, as they'll kill your momentum.

Hug the right wall as you drop through the next shaft to collect another ? Coin. Enter the current it creates, then drop down the center past the three moving platforms.

Continue to hug the right wall, turn invisible to go through the wall, and grab another ? coin and enter the air current that activates. Now just drop through the remainder of the level, turning invisible to bypass the walls, until you reach the goal for your star.