From the Super Mario Wiki
Piranha Gardens, or Acorn Plains-5, is the fifth course of Acorn Plains in New Super Luigi U. It is unlocked by completing Rolling Yoshi Hills, and its own completion unlocks Lemmy's Lights-Out Castle.
The player begins the level next to a group of rising and falling rocky platforms, where a Koopa Troopa, a Hammer Bro, and two sets of ? Blocks are found. A Red Ring is found, along with a mini Warp Pipe that leads Luigi to an underground area, where a path of coins above water leads to a Hidden Block containing a 1-Up Mushroom. A group of rising platforms are found, along with two Big Piranha Plants. Brick Blocks and two ? Blocks are found with a Hammer Bro on them. A 1-Up Mushroom is found in a Brick Block in the top row. A Koopa Troopa is then seen, along with three more Big Piranha Plants. A Coin Block appears above a rising platform, followed by the Goal Pole.
To the right of the second Star Coin, there is a bush shaped like Luigi.
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