Secret Course 25
From the Super Mario Wiki
The course starts with three ? Blocks, all of which contain a Super Star, which can be used to defeat the Scuttlebugs and Swoops in the course. The first Bonus Medal is inside the ? Block at the top of the second slope. The second Bonus Medal is inside another ? Block at the top of the third slope. The third Bonus Medal is inside yet another ? Block at the start of the fourth slope while the fourth Bonus Medal is found at the top of the fourth slope among Brick Blocks. The fifth and final Bonus Medal is found by jumping off the two sets of Hard Blocks right before the Goal Pole.