World 2 (Super Mario World 2: Yoshi's Island)
From the Super Mario Wiki
World 2 is the second world of the game Super Mario World 2: Yoshi's Island and Yoshi's Island: Super Mario Advance 3. It consists of 10 levels (including the Bonus Game for the SNES version), and like every other world, it has 6 regular Levels, a Fort, a Castle, an Extra Level, the Scratch and Match Bonus Game (SNES Only), and a Secret Level (GBA Only). Most of the levels in the world are set on forested mountains or in dusky uplands.
List of Levels in World 2
Here are all the levels in World 2:
The first appearance of Koopa Troopa alongside with Koopa Paratroopa. This level is very mountainous and has a lot of falling rocks that will crush Yoshi or simply fall into a pit. Poochy also makes an appearance in this level. In one area, the screen scrolls slowly upwards as Yoshi has to avoid falling rocks that pile-up on each other Tetris-style. Also, this is the first time Baby Mario can morph into Superstar Mario.
Lakitu, Cactus Jack, and a regular Cactus make their first appearances throughout the game. This stage has a lot of Shy Guys in it, and is also the first time that Yoshi will be able to tranform into a Train.
The player will be outside in the start of the level. They will soon be in an underground room once they hit the ? Cloud containing a door. The player will be in a smoke filled room, and will carefully advance to reach another room that will lead outside to a beachside area.
The boss of World 2, along with two Green Shy Guys aiding him. This level contains many areas in which Yoshi will be inside a pipe, along with thorns. Yoshi will also be able to transform into Train Yoshi in this level.
The second Extra level in the game. The player will have to quickly advance while hitting the ! Switches and avoiding Piranha Plants. There is also a pipe in the beginning that contains stars, which will be the only time the player will get them too.
This level contains a maze which is very complex. There will also be a section in which the player will have to ride Flatbed Ferries in order to advance throughout the level.