Koopa Troopa Cave

Koopa Troopa Cave, otherwise known as World 1-2, is the second standard course of World 1 in Super Mario 3D World. The course takes place in an underground cave with Koopa Troopas, Goombas, and clear pipes. It is unlocked by beating Super Bell Hill and its completion unlocks Chargin' Chuck Blockade and a Toad House.

Layout
The course starts on a grassy hill with a pipe nearby which leads to an underground section. A Clear Pipe leads him to a ? Block containing a Fire Flower. Another pipe leads him to a platform area with a + Clock and a Checkpoint Flag nearby. After passing a pipe network filled with Goombas and Koopa Troopas, the player can enter a nearby pipe leading to the overworld and the Goal Pole.

Green Stars

 * Green Star 1: Before the checkpoint, between some moving cloud platforms.
 * Green Star 2: The player needs to climb three purple blocks to find a purple mystery box, they then need to jump into it and defeat the two Koopa Troopas to reveal the second Green Star.
 * Green Star 3: Near the end of the level, players will find a Goomba Stack with the final Green Star in the middle of the stack.

Stamp

 * Just after the clear pipe to the last room, there is a rectangular question block. Mario needs to get on top of it and jump to reveal a hidden rectangular question block. Mario then need to jump on top of that block to reveal another, reaching a ledge. Mario needs to enter the clear pipe on the wall to warp into an enclosure below the ledge containing the stamp and several coin stacks.

Secret Warp to World 2

 * Cat Mario is required. Slightly to the right of the clear pipe leading to the stamp, Cat Mario must climb the wall to reach the ledge with an orange Warp Pipe. Once entering the pipe, the level will end automatically and Mario will travel through the pipe underneath World 1 and come out at the beginning of World 2.

Enemies

 * Koopa Troopas
 * Goombas