So you might know about the minus world "glitch" where you go to a never ending water area that looks like 2-2. But, what you might not know is there is more to the minus world on the Famicom Disk System version of the game. In fact, in that version you can progress beyond -1 and all the way to -3. Its a trip and you should check it out!

Sources:

VGMaps Super Mario Bros World -1 NES map - NES/Famicom Cartridge Version

VGMaps Super Mario Bros World -1 NES map - Famicom Disk Version

VGMaps Super Mario Bros World -2 NES map - Famicom Disk Version

VGMaps Super Mario Bros World -3 NES map - Famicom Disk Version