Super Mario Land 2: 6 Golden Coins/Pumpkin Zone

You have reached the spooky Pumpkin Zone, which is the residence of another holder of a golden coin: Sabasa the witch. In order to get to her lair and defeat her, you'll need to make your way through an underground tunnel, across a cemetary and inside an abandoned mansion. Don't let the macabre enemies in this zone freak you out!

A dark tunnel
This treacherous passageway is filled with traps and enemies, so stay on your toes. Other than the enemies you've already met, you will also encounter J Sons, which are walking hockey masks that are basically goombas, as well as the Boos, which will chase you when you're not facing them, but hide shyly when you do. You will also find the sole Kurokyura in the game, a vampiric enemy that attacks by throwing bats at you. In addition to that, you'll have to watch out for spikes that fall from the ceiling and deadly spiked balls fixed on rails.

The first two ceiling pipes you get to will take you to an area above ground with two boos and some vanishing blocks. You need to make your way across these invisible blocks, memorizing their positions when they flash, to get to the item blocks at the top, though the only worthwhile block is the middle one, which gives you a 1-Up. Additionally, if you jump on to the ledge with the Kurokyura near the end of the level and you have the carrot, you can use your improved jump to reach an alcove that has a block containing a 1-Up. To reach the bell, you will need to jump from the ledge with the Kurokyura, as it is too high to be reached at all from the lower path.

The Youkai cemetary
Dozens of wierd and bizarre monsters roam free in this creepy graveyard. You will encounter several enemies based off of Japanese folklore, like the Karakaras which are umbrellas that shoot up and float back down, the one-eyed Kyororos that will charge at you as soon as they spot you, the unnamed fire spirits that float around the level as well as the Bero, indestructible lanterns that attack with tongues, though they can also act as platforms. This level also contains a fair amount of swimming, so a fire flower is useful for self-defense.

After the gravestones at the start, you will reach a bunch of pipes. Jump down the third pipe to enter a well for some extra coins and a fire flower. Later on, after a short water section will be a simple pipe maze. Don't grab the mushroom is you have a better power-up, as it will actually downgrade you. Do grab the 1-Up at the right of the highest level though. After the pipe is a bunch of breakable blocks that will give you rewards depending on which column you choose to go drill through. The second column leads you to a carrot, the third column gets you some coins, the fifth column gives you a fire flower while the last column nets you a 1-Up, though you can also grab it after you've drilled down another column. The ending bell is a little harder to reach, as it need you to use the carrot's glide as well as the thrust from jumping off of one of the Karakaras to reach the roof of the shack, letting you ring the bell.

There is a secret exit in this level that not only tests your curiosity, but also your evasion. You can find out where it is in the spoiler below.

A secret coin haven
From a certain alternate exit from the cemetary, one can enter a blocked off mushroom patch outside Pumpkin Zone. Right from the start, you can obtain a carrot from the sole block, which will let you fly across several huge patches of coins, but that's not all that this bonus level offers. As you near the exit to the level, jump over it and dash right to the very end, where you will find a Star. Just grab the Star and run to the left, taking out as many goombas as you can, to get a bunch of extra 1-Ups.

The haunted mansion
This level is focuses more on platforming that on enemies, and most of enemies you encounter can't even be defeated. The only new enemy you will face is the Teregoomba, the undead spirit of a goomba. You will have to navigate across invisible blocks a lot in this level, so be patient and progress carefully.

In the pipe just before the check point bell, you can enter a secret chamber that lets you grab a fire flower and a 1-Up, though you'll need to break a specific block, otherwise you won't be able to access the the blocks on the higher levels. To reach the bell, simply use the invisible blocks to reach it.

There is actually a second hidden exit in this zone, and it is located in this level. Read the spoiler below to find out where.