World 2-5 (Super Mario Bros. 3)
From the Super Mario Wiki
World 2-5 is the fifth main level and the seventh level overall of Desert Land in Super Mario Bros. 3. It is accessed by completing World 2- and its own completion will open the way to World 2-. Additionally, this level introduces Chain Chomps.
The player starts on a plain with several Wood Blocks and a Chain Chomp, and in one of the two ? Blocks nearby is a power-up. Past the stacked Semi-Solid Platforms is another Chain Chomp and a Koopa Troopa walking along a row of Brick Blocks, underneath of which is a Wood Block the player can bump to get a power-up. Across a pit are more Semi-Solid Platforms with Goombas and another Chain Chomp. In the area afterward with an enclosed space with Brick Blocks at the bottom; the player can kick a Koopa's shell into the narrow area to create a Vine that leads to a secret room with coins and a P-Switch, the exit pipe of which will drop the player into a floating Semi Solid Platform area where a power-up can be collected. Afterward is the goal with a Chain Chomp underneath it.