World 5 (New Super Mario Bros. Wii)
From the Super Mario Wiki
World 5 (also known as the Jungle World) is the fifth world in New Super Mario Bros. Wii. The world is a tropical rainforest with poison, which can be seen in some levels. Bramble vines block some of the paths. They will occasionally change positions. There are eight levels in this world, two of them being castle levels that are guarded by Iggy Koopa, and one being a Ghost House. . It also has a total of nine exits. There is also a Warp Cannon that sends the player to World 8.
This world features one Toad House of every color; red, green, and yellow. On the map, there are Stalking Piranha Plants. Mario and co. can get attacked by one and be forced to play in the Enemy Course. There are a total of three Enemy Courses in the area. This makes it one of the only worlds in the game with several enemy courses, and the one with the most. Also, once Iggy has been defeated in the castle, the bramble patches will disappear completely.