Super Mario World/Donut Secret House

Donut Secret House is one of two ghost houses in Donut Plains. After transversing the first "room" left-to-right, and entering the second room, there will be a circular arrangement of Boo Buddies. There will then be a small platform with five coins on it. In order to get to the normal exit, these coins must first be taken, and then the P-switch obtained from the leftmost end of the room, brought back to the small platform, and activated. A blue door will then appear, through which is the non-secret goalpost.

In order to get to the secret exit, obtain the P-switch, bring it to the arrangement of yellow blocks in the center, and activate it. A row of question-mark blocks will appear, making it possible to stand on what was previously empty space. Stand on the center question-mark block and hit the yellow block immediately above. A vine will appear, which must be climbed. At the top is a long platform extending to the right, and there is a blue door at the rightmost end. (The P-switch must not have timed out in order for the door to still be there.) The door leads to a battle-room, where there is one Big Boo and three Boo Buddies. The Big Boo must be defeated by throwing at it the gray blocks that make up the floor. Be careful not to create a hole in the floor and fall through it. After the Big Boo is hit three times, it will be defeated, leading to Star Road.