Bob-ombs and regular bombs populate this underground level. Many of the secrets here require you to use these bombs to blast open walls or clusters of ? Blocks.
Green Star #1
Early into the level, you encounter a Goomba Tower next to a Crystal BLock Wall topped by a Red POW Block. Use the nearby bomb to blast open the wall to free the first Green Star.
Next to a pair of small rotating platforms is a Baddie Box dispensing Bob-ombs, and a chain of Crystal Blocks lined with Red POW Blocks along the wall. Trigger the destruction of the chain by hitting a Red POW Block. A 1-Up appears on another section of the wall, and you have to move fast to catch it.
Green Star #2
Just past the Checkpoint Flag is a circular platform rotating around a smaller platform. A Rabbit leads you on a merry chase around these platforms. Catch it to win the second Green Star.
Stamp
Two short Goomba Towers carrying bombs roam just past the Rabbit with the Green Star. Use one bomb to break open a weak section of the wall, and another to blast open the chain of Crystal Blocks and Red POW Blocks. Then enter a secret passage that takes you right to the Stamp.
Green Star #3
The final Green Star requires you to use a Cloud Cannon that’s easily reached via a Clear Pipe. The cannon shoots you to a special bonus zone where you must light up all the Color Panels on the ground to release the Green Star. You can speed this process up by using the Red POW Blocks and Bob-ombs in the area.
The final run to the level exit can be cleared by triggering the destruction of the Red POW Block chain on the wall. This makes it safe to use the Dash Panel to dash to the pipe. At the Goal Pole zone, you can use a Tanooki Power-Up, or a Bomb to break blocks and create an easy way to reach the top of the Goal Pole. You can also break blocks with the touch screen.