Soda Jungle

Soda Jungle is the jungle world in New Super Mario Bros. U and is the largest world in the game, with a total of 12 courses, the most of any other world. This world, as the name implies, takes place in a jungle that's inspired by Big Island from Super Mario Bros. 3, Forest of Illusion from Super Mario World and World 5 from New Super Mario Bros. Wii in terms of appearance, layout and theme as the jungle is giant-themed within both the world map and the normal levels, as well as big enemies or big variations of small enemies, like Grand Goombas and Gargantua Koopa Troopas. The dead trees in the center of the jungle leads to a haunted area, containing a few extra courses, including Boo enemy courses. When the player enters the area, the area pixelates before loading again. The name is derived from soda and is a reference to Soda Lake. There are twelve levels in this world, with the first Airship level appearing before entering the section, five normal levels in the outer areas, two that are in the haunted area along with the second Ghost House and the Boo Enemy Courses, a secret level, the Tower level and Castle level. One colour of each Toad House can be found here as well.

There are several ways to enter this world. Completing Wendy's Shifting Castle or Larry's Torpedo Castle will bring Mario to The Mighty Cannonship, the first airship in the game. However, completing Blooper's Secret Lair or Piranha Plants on Ice, Acorn Plains and Layer-Cake Desert's secret levels respectively, will immediately take Mario to Jungle of the Giants.

The boss of this world is Iggy Koopa, who is the boss of both the fifth world in the game (like he was the boss of World 5 in the Wii predecessor) and the boss of a big-themed world (much like how he was the boss of Big Island).

Before Soda Jungle

 * : The Mighty Cannonship: The first Airship course in the game.

Inside Soda Jungle

 * Soda Jungle-1: Jungle of the Giants: This level features Mega Goombas, Gargantua Koopa Troopas, giant blocks and giant pipes.
 * Soda Jungle-2: Bridge Over Poisoned Waters: The second level of Soda Jungle.
 * Soda Jungle-3: Bramball Woods : The third level of Soda Jungle.
 * : Snake Block Tower: The Tower level of Soda Jungle.

Haunted Area

 * : Which-Way Labyrinth: A Ghost House.
 * Soda Jungle-4: Painted Swampland: A haunted level with Vincent van Gogh's The Starry Night painting as reference for the background, Toxic Water and Circling Boo Buddies.
 * Soda Jungle-5: Deepsea Ruins: A haunted forest level featuring a lake filled with stationary stone heads.

Outside Soda Jungle

 * Soda Jungle-6: Seesaw Bridge: The sixth level of Soda Jungle.
 * Soda Jungle-7: Wiggler Stampede: The seventh level including a large amount of Wigglers.
 * : Iggy’s Volcanic Castle: The Castle level of Soda Jungle with Iggy Koopa as the boss.
 * Soda Jungle-Para-Beetle: Flight of the Para-Beetles: A secret level with Para-Beetles and King Bills.

Challenge Mode original courses

 * Mole to Goal
 * A challenge where Mario has to avoid groups of Circling Boo Buddies and get to the goal for a certain amount of time.

Trivia

 * This is the only world in the game with more then 1 section (it has a total of 3 different sections): The haunted forest sub-area, the outside and the inside. This is similar to World 3 of New Super Mario Bros. Wii, which also had multiple sections.
 * Interestingly, every world before Soda Jungle leads to the latter, either by world-skipping shortcut or completing the previous world's castle.