World 5-3 (Super Mario Bros. 2)
This level has a hidden Subspace Warp to World 7 that can be reached with any of the playable characters. Near the start of the level, right after climbing up the ladder, there will be a platform on top. Luigi can Power Squat Jump up on top of it and find the Magical Potion. After entering Subspace, the player needs to enter the jar and will be warped to World 7. If played as a different character (Mario, Toad, and Princess Toadstool), they can ride an Albatoss to the platform.
Throughout the level, Albatosses continuously drop Bob-Ombs; once the player reaches the underground cavern, various walls must be destroyed, and there are a few Pansers and Ostros. Unlike the other worlds in the game, the player does not enter a castle, but the player encounters a room containing Sparks, Bob-Ombs and walking Pansers. Since the level lacks a locked door, the key is absent. Once outside again, the player must ride a Pidgit to cross a large gap. After the four pink Shyguys, the player fights and defeats a Red Birdo and then encounters a boss, Clawgrip (Mouser in Yume Kōjō: Doki Doki Panic).