Rock-Candy Mines is the mountainous sixth world of New Super Mario Bros. U. It is physically the smallest world and it lies east of Acorn Plains, Sparkling Waters, and Soda Jungle, southeast of Layer-Cake Desert, Frosted Glacier, and Meringue Clouds, and south of Peach's Castle. Rock-Candy Mines is a world filled with tall, pillar-like mountains in somewhat irregular shapes. The name is derived from rock candy. There are ten levels in this world, with seven normal levels, two Towers and the Castle level. The boss of this world is Roy Koopa.
There are multiple ways to enter this world. One is to complete Iggy's Volcanic Castle, Soda Jungle's castle, normally. The other two are to complete Fliprus Lake or Skyward Stalk, Frosted Glacier and Sparkling Waters' secret levels, respectively.
||This is a clifftop level that features Yoshi, Berries and Fuzzies.
||Another cliff level over the water, where Porcupuffers attack. Many Urchins can be found, too.
||The last tower where a Boom Boom is the boss. The main enemies in this tower are Grrrols.
||This level features Chain Chomps, Waddlewings and tilting stands.
||Light Blocks, Dark Tower
||A dark cavern filled with giant Glow Blocks, Swoopers, Bob-ombs, and ? Switches that light the Glow Blocks when activated.
||Walking Piranha Plants!
||A mountain full of Stalking Piranha Plants, moving yellow platforms, and chains.
||Thrilling Spine Coaster
||A dark cave level with a Poisoned Water lake and Spine Coasters.
||The first and only tower with Sumo Bros. and Boss Sumo Bro. Elastic platforms are found here, and all the Sumo Bros. in this tower are found on them.
||This underground level is filled with moving iron blocks, Piranha Plants, Super Piranha Plants, and elastic bars.
||Roy's Conveyor Castle
||This castle is full of conveyor belts and steel crates that can often squish Mario.
 Names in Other Languages
||Mines de la Molasse
||Miniere di caramella
- Rock-Candy Mines is the only world in New Super Mario Bros. U to have two towers.
- This is the last world where Boom Boom is fought, as Kamek takes his place in the Meringue Clouds tower, and the only world to have a Sumo Bro. as a boss.
- The Sumo Bro. boss does not appear on top of the tower on the world map before Mario enters it. He does appear briefly after his defeat, though.
- This world, along with Peach's Castle and Superstar Road, are the only worlds in the game to not have Enemy Courses.
 New Enemies