World 2-4 (Super Mario Bros. 3)
From the Super Mario Wiki
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World 2-4 is split between a lower path and an upper path.
The lower path is a plain broken up by pits and ledges, with several Koopa Troopas and Boomerang Bros. To collect the power-up in the ? Blocks over the pit or on the ground, the player has to kick a Koopa Troopa's shell into the block. After the Venus Fire Trap in the pipe and the second Boomerang Bro. are several high ledges with Coins between them, followed by the goal.
To reach the upper path, the player needs to be powered-up with a Super Leaf, which the player can collect from the ? Block over a pit if needed. By building up the Power Meter and flying into the Brick Blocks directly above where the player started, the player can reach an oasis, which has a P Switch hidden in one of the blocks. Afterward is a long path with Coins and Coin Blocks hidden as Brick Blocks, followed by some Koopa Paratroopas. At the end of the path are several Coins and Brick Blocks, along with a P Switch hidden in the block above the last. Finally, there are some descending Note Blocks, with the last of which holding a power-up, leading to the goal.