World 5 (Super Mario Bros. 2)
World 5 is the fifth world in Super Mario Bros. 2, and all subsequent remakes, most notably Super Mario Advance. Like World 1 and World 3, it has a traditional grass-type theme, although some of World 5 takes place at night. This world introduces Birdo's green form, the hardest form of Birdo in the game because she fires only fireballs and must be defeated using other projectiles. In the original Yume Kōjō: Doki Doki Panic, the boss was a repeat of Mouser, but for the SMB2 version, he was replaced with a new boss, Clawgrip the crab.
This level starts with the player staying for very little in the outside, as the rest of the stage takes place underground. There is an extremely long waterfall that can initially be passed through the falling wooden platforms, then by jumping from Trouter to Trouter. The timings are strict, and it's advised to play as Luigi or Princess Peach only (and either of them must land on at least one of the Trouters before performing the larger jump, as it by itself is not enough to overcome the chasms). This is the first level in the game where a completely fire-shooting Birdo is fought.
This level is set mostly on land, unlike the previous stage; there aren't many obstacles, so most of the difficulty is based on the diversity of enemies (such as Hoopsters and Porcupos) found. At some point, a large mountain must be climbed through various vines, then the player has to fall through a deep hole full of spikes, which can only be avoided with quick reflexes. Birdo is fought over a cascade.
This level has a hidden warp to World 7 that can be reached with any of the playable characters but works best if the player plays with Luigi, because he can jump the highest. Near the start of the level, right after climbing up the ladder, there will be a platform above Luigi's head. He must Super Jump up on top of it, and find the magic potion. After entering dream world, he needs to enter the vase and will be warped to World 7. If played as a different character, requires to jump on top of an Albatoss an fly to the platform.
For those who venture through the level, a tough voyage awaits. First, there is a field constantly nuked by Albatoss birds laying bombs; once the player reaches the end, an underground cavern follows, where various walls must be exploded, and where a few Pansers and Ostros must be beaten. Unlike the other worlds in the game, there is no fortress to explore, so what is visited instead is the interior of a tree full of Sparks, Bob-ombs and walking Pansers; there is no locked door, so no key is collected, and Phanto is not seen anywhere. Once outside again, the player has to cross a very long chasm with the help of Pidgit, so that Birdo is found and defeated, leading to the lair of the boss, Clawgrip.