Continue through the level until you reach the area where there is door partially covered by cloud between two Shotzos. Find a way down to this door by going to the left and sneaking under the clouds.

In the next room, you'll find two Rockys and a 1-UP. Grab a 1-UP, and the stone ability from the Rocky if wish.

Using the stone ability, you can just drop straight down the level with ease! Watch out though, because the bottom of the level is only blocks! When you reach a door, don't stop - keep going!

Uncovering a few of the blocks to the left is a hidden door! Go through to find the switch!