Walking Piranha Plants! is the fifth level of Rock-Candy Mines in New Super Mario Bros. U. It is unlocked via completion of Waddlewing's Nest or Light Blocks, Dark Tower. Its own completion opens the path to a blue Exclamation Mark Switch and the course Screwtop Tower, while the secret exit opens the path to a red Exclamation Mark Switch and Screwtop Tower.
As the name implies, the main enemies of the course are Stalking Piranha Plants, while enemies like Goombas and Koopa Troopas are also present. Another gimmick of the course are chains which the player can use to swing across gaps with.
The level begins with a chain that is used to reach a row of Wobble Rocks above a pit. A ? Block containing a power-up is found, along with a Goomba and a Koopa Troopa. Another Wobble Rock and a chain are found, followed by a group of Stalking Piranha Plants. More chains are found above Stalking Piranha Plants. Another section of chains over Stalking Piranha Plants follows, with the Stalking Piranha Plants on horizontally-moving lifts. The Checkpoint Flag is then found. A Roulette Block is found near a Goomba and some Koopa Troopas. Another row of Stalking Piranha Plants follows, along with more Stalking Piranha Plants on lifts. A Red Ring is found above one of the lifts. Another chain is found, along with the Goal Pole.
- Star Coin 1: After a series of Stalking Piranha Plants, hidden inside a wall.
- Star Coin 2: Shortly after the first Star Coin in a gap in the sky which leads to the area with the second Star Coin.
- Star Coin 3: Beneath an orange bridge, Flying Squirrel Mario is required to reach it.
Before the final chain is a hidden wall with a Warp Pipe that leads to the secret exit. It unlocks a path to a red Exclamation Mark Switch and Screwtop Tower. This switch serve as an access switch to the second entrance of Roy's Conveyor Castle in case Thrilling Spine Coaster is not yet unlocked.