New Super Mario Bros. U: Meringue Clouds-3 -- Switchback Hill

The switchbacks in the level are platforms with arrows on them. If you stand on them, they move in the direction of the arrow. If you jump off them, they go in the opposite direction back to where they started. The first Star Coin is under a ledge next to a Bill Blaster. Go a little to the right and you'll see two switchbacks. Take the one going left to the Star Coin. Be sure to duck to avoid the Bullet Bills. Keep going right and you'll see a bit of a puzzle. There's a tall Bill Blaster in your path. To reach it, you'll have to transfer switchbacks going first to the left, then to the right. Past the tall Bill Blaster, you'll see a large switchback that moves vertically. Let it drop down a little, then immediately go to the right and wall jump up into the alcove for a hidden pipe. This leads to an area with a path to the second Star Coin. Return to the main level and the midpoint is nearby. There's a switchback moving down. Trip it to get it moving and go down and right for a hidden area. There's a POW Block. Using it will make the third Star Coin fall onto a switchback and make it move to the right. You'll have to follow it below on lower switchbacks unless you can fly to get it. Before you reach the flagpole, the switchback will go into a wall and let the Star Coin drop into the void. Be there to catch it to get it. Go past some Parakoopas on the stairs to reach the flagpole. This opens the path to the Fort.