World 4-C is a secret level in New Super Mario Bros. 2. To unlock this level, the player has to locate the secret exit in World 4-.
Mario begins on land with two Fuzzies in gaps on the floor. There is a hole which Mario must drop down, taking him into a cave underground which is full of stalagmites and stalactites. The cave is full of Fuzzies, Brick Blocks and POW Blocks, where Mario can find a Fire Flower from early in the level. After passing some more Fuzzies and stalactites, the Checkpoint Flag can be found. Following that are moving yellow platforms on tracks, where several Fuzzies also lie. More platforms can be found along with more Fuzzies and finally the exit pipe. Back in the overworld, there are several narrow cliffs between Fuzzies, and at the end is the Goal Pole.
Completing this level unlocks World 4-5, skipping World 4-3 and World 4-4.
- Star Coin 1: Early in the level, the Star Coin can be found above some Brick Blocks with a Fuzzy. Mario should not activate the POW Blocks below as it will destroy the blocks needed to obtain the Star Coin.
- Star Coin 2: Just after the checkpoint, there are yellow moving platforms. At the top platform, Mario must jump to a ledge on the left where a large Fuzzy can be found along with an inaccessible pipe. Mario then have to navigate past the Fuzzy to find another pipe which can be entered, taking Mario to another room full of Fuzzies and two POW Blocks. The Star Coin above the POW Blocks can be obtained by defeating the Fuzzies with the POW Blocks and then climbing up and obtaining the Star Coin.
- Star Coin 3: Instead of entering the exit pipe, Mario must Wall Jump up the rightmost shaft when the Fuzzy leaves the area. The Star Coin can be found there.