World 4-2 (Super Mario 3D Land)
From the Super Mario Wiki
World 4-2 is the second course of World 4 in Super Mario 3D Land. The level takes place underground and features several Goomba Towers and Inky Piranha Plants. The level also contains a hidden Warp Zone that takes Mario to World 5.
Mario will start in an area with low and high platforms, that come in yellow and blue colored variations. There are a Goomba Tower and Inky Piranha Plants. To the far left side, Mario will find a hole where he can enter. There are two ? Blocks (one contains a single coin and the other, a Fire Flower) and a ! Block to create yellow blocks to reach in two bouncy platforms, that lead to an small area with another ! Block to get to a smaller place, where Mario find another Inky Piranha Plant and a ! Block. The yellow blocks reach in a bigger room, with a ! Block, another Goomba Tower, a rectangular ? Block with two Coins and a Fire Flower. Mario can use another trampoline to go to a hole in the ceiling, where are another Goomba Tower, another Inky Piranha Plant and another ! Block. In a vertical room in the left, the plumber uses Trampolines to collect coins and reach on a Warp Pipe that conducts he to the final part. In the final area of the level which is outdoors , Mario can use a last ! Block to create yellow blocks that go toward the Flagpole.
Near the end of the level, Mario must bounce higher on the third bouncy platform, then wall jump to reach a higher area which leads to an orange pipe. Entering it will warp Mario to World 5. As with World 1-2, this warp is a reference to World 4-2 of Super Mario Bros.