From the Super Mario Wiki
Underground Mysteries is Level 2-2 of Yoshi's Island DS. The level takes place in an underground cave.
The level starts with Yoshi near a pipe which leads to a cave with a Chomp Rock and a Stork Stop nearby. Baby Donkey Kong's DK Dash Attack is needed to get past some nearby soft rock and into the next area. Here, the player must get through a narrow passageway filled with Piranha Plants and become a Mole Tank to smash through more soft rock. The Yoshi must hit the Yoshi Block and continue to another area where some enemies, a Stork Stop, and a Middle Ring await. Now, all three babies and their respective abilities must be used to get to a pipe leading to the overworld. The player must get past a Windbag and some Stilt Guys to reach the goal roulette.
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