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, and like every other world, it has six regular levels, a Fort, a Castle, an extra level, the Scratch and Match Bonus Game, 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 Para-Koopa. This level is very mountainous and has a lot of falling rocks that can 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.
The player starts outside in the beginning of the level. They are soon in an underground room once they hit the Winged Cloud containing a door. The player is then in a smoke filled room, and carefully advances to reach another room that leads 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 is inside a pipe, along with thorns. Yoshi is also able to transform into a train in this level.
The second Extra level in the game. The player has to quickly advance while hitting the ! Switches and avoiding Piranha Plants. There is also a pipe in the beginning that contains stars, which is the only time the player is able to get them too.
This level contains a maze which is very complex. There is also a section in which the player needs to ride Flatbed Ferries in order to advance throughout the level.
Collecting 800 points (700 in the remake) unlocks Scratch and Match to play anytime.