This is a pretty complicated clear pipe maze. When you come to a junction, signal with the joystick where you want to go in advance so it will register. First, go through the front loops a couple of times to get the invisible coins. Go to the right, then up to get the first gem. You may need to wait so you can avoid the Fuzzies in the loop as well. You'll want to head left, then down to get to the left side. The second gem is in a loop with some Fuzzies. Do not use the nearby pickax to defeat them. Instead, once you get the second gem, grab the pickax and head left, up, and right to get the third gem surrounded by spike balls. Head to the right, then to the back of the maze. There will be two sets of Fuzzies looping around back there. Use the empty loop to wait until you get a favorable time to enter the loops with the Fuzzies. Exit to the right and you'll find the Star. Go past it and enter the pipe on the other side to reach the Gold Mushroom, then make your way back to the Star.
Special Challenge: Collect 70 coins.
You'll need to collect all of the coins, including the Gold Mushroom to complete the challenge.