Available only in the Nintendo Switch version and in Link's Awakening DX when played on a system that can play the game in color, this dungeon is hidden in the graveyard.
Prepare for the Color Dungeon
You can enter the Color Dungeon after you have completed Bottle Grotto and taken BowWow back to Madam MeowMeow in Mabe Village.
Before you go to the dungeon, you might want to buy bombs from the Mabe Village shop. You will also need Magic Powder. In the Nintendo Switch version, you will be able to buy Magic Powder at the entrance.
Reach the Dungeon
You can optionally get a clue to finding the color dungeon if you have the Pegasus Boots. You can go to the library in Mabe Village and use the boots to knock down the book that is on the top of the shelf in the library. The book tells you how to find the new color dungeon:
3^ 4> 5^ 2< 1v
So go to the graveyard and go to the southeast corner, where the graves match the pattern in the book. Push the graves in the order of the numbers shown in the book. In other words, push the bottom-right grave down, push the bottom-left grave left, push the upper-left grave up, push the upper-middle grave to the right, and push the upper-right grave up. Stairs will appear. These stairs lead to the Color Dungeon.
Open the Dungeon
In the dungeon entrance, talk to the skeletons. If you are playing the Game Boy version, you have to say which color each of them is wearing, and if you say the correct one, they will move aside. They will tell you that you need to bring Magic Powder. In the Nintendo Switch version, they will offer to sell you some. In the Game Boy version, be sure to go get some if you don't have any. You can get some for free, and a free upgrade, by lifting a stone in the Mysterious Woods to find hidden stairs. These stairs lead to a well underground. Use Magic Powder on the well and a bat will appear. It will upgrade your bag of Magic Powder to hold 40 sprinkles of powder, and it will automatically fill up your bag.
Go north from the skeletons.
Get the Stone Beak
In the next room, approach the monsters in the tiles and then run away while the Camo Goblin moves toward you. When the goblin pops up, hit it with your sword to kill it. The door will open.
Go east through three rooms (the colorful tiles make you bounce, so go across carefully; landing on a red tile makes it disappear) to reach a room with two differently-colored Orb Monsters, and two differently-colored in the floor. Hit the monsters to stun them, then pick them up with the Power Bracelet and throw them into the hole of the matching color. A chest will appear. It contains the Stone Beak.
Get the Compass
Go west two rooms from where you got the Stone Beak. You should be in the room with an owl statue. Check on the owl statue to get a hint about the puzzle. It says to make all the objects match.
Hitting a statue changes the one that you hit, and the two next to the one that you hit. To solve the puzzle, hit a corner statue, then hit the one in the opposite corner. If this doesn't work, try it again with the other corners. A chest appears. It contains the Compass.
Open the Hidden Rupee Room
If you have bombs, bomb the south wall of the room where you found the Compass. A hole will open one square left of the owl statue on the opposite wall. Go through to find a hidden room that contains 140 rupees.
Get a Key
Go east from the room where you hit the statues and got the compass, then go east from the room with colorful floor tiles. From the room with the round holes in the floor, go south. Kill the Camo Goblins hiding on the colorful tiles, then go west to the next room.
Bounce over the tiles, remembering that if you land on a red tile, it disappears. Kill the Bone Putters, then open the chest to get a key.
Get a Second Key
Use the one-way door in the north wall to leave this room.
Go east to the room where you threw the Orb Monsters into the holes. Go north from that room.
Bounce over the tiles, but avoid the red tiles. Go north through the door.
The owl will tell you to make all the statues match what the upper-right and bottom-left statues are currently set to. This time, there is a third color. Hit the bottom-right statue, then hit the upper-left statue twice. A key falls from the ceiling. Take it.
Reach a Mini-Boss
Go east. Kill the Camo Goblins that are hiding in the tiles, or ignore them. Go north through the locked door.
Mini-Boss: Giant Buzz Blob
When Giant Buzz Blob has legs, it will electrify you if you hit it. Use Magic Powder to turn into a round blob. You can safely hit the round blob with your sword. It will hop around, so run away from it until it lands, then quickly turn around and hit it. When it goes back to its electrified form, use Magic Powder to transform it again. The blob will shoot lightning bolts diagonally, as well as horizontally and vertically, so be careful to avoid these.
Get the Nightmare's Key
Go west after you kill the Buzz Blob. Push the top block left, the bottom block left, then the middle block up or down. Go to the chest and open it to get the Nightmare's Key.
Reach the Next Mini-Boss
Go back to the room with bouncing tiles and a locked door in the north wall. Go through that locked door.
Mini-Boss: Stone Hinox
Bombs work well against the Stone Hinox. If you don't have any, carefully hit the Stone Hinox with your sword, but in the Game Boy version, be aware that you will be knocked back when you hit it. This might cause you to be pushed into the spikes. The Stone Hinox will jump and cause the ground to shake, also causing boulders to fall from the ceiling.
Get the Map
After Stone Hinox is dead, go through the west door.
There is a switch hidden under the upper-left pot. Carefully make your way to the upper-left corner of the room, then lift the pot and step on the switch. Then go through the north door.
Go around the room killing all the hidden Zols and the red Zols. After they are all gone, a chest appears that contains the Map.
Get a Third Key
Go east from where you got the map. Hit the Orb Monsters to stun them, then throw them into a hole of the matching color (in the Nintendo Switch version, each monster also has a shape on it that corresponds to a shape on the floor). When all the orbs are in the correct holes, a key appears. Take it.
Reach the Nightmare's Door
Go back to the room with the bouncy floor tiles and go west from there.
There is another statue puzzle here. If you talk to the owl, it tells to make the statues blue (in the Nintendo Switch version, it says to make all the tiles square). To do that, hit the middle-left statue, the upper-middle statue, the middle-right statue, then the lower-middle statue. (You can start with a different one, but be sure to go clockwise or counter-clockwise.)
Go through the north door.
There are hidden green Zols in the floor tiles here. You can ignore them or kill them, then go through the locked door.
Walk to the crystal and hit it while standing on the color blocks. Go to the right, then go up and unlock the Nightmare's Door. Go through.
Hardhit Beetle
This creature starts with a blue orb. The more you hit it, the more its color turns from blue to red. However, the Hardhit Beetle heals itself over time, so if you don't hit it quickly, it will go back to blue. After you have done enough damage, the Hardhit Beetle tells you to "take your time", but this is just a trick. You should attack as quickly as possible. Hardhit Beetle can make Stalfos attack you, and it can throw spinning blades at you. The Bow and Arrow works well, as does the Magic Rod. If you don't have those, try jumping over the blades that the Hardhit Beetle throws, and swing your sword at the same time.
In the next room is a Great Fairy who can give you special armor. NOTE! In the Game Boy version, you can never go back to the Green Clothes if you take the Red or the Blue Clothes! If you are playing the Game Boy version and want to keep wearing the Green Clothes, don't go to the room after the Hardhit Beetle's room!
Get the Red or Blue Clothes
In the next room, a Great Fairy will offer to give you the Red Clothes or the Blue Clothes. You can only choose one. But you can go to the end of the dungeon again if you want to switch the color. The doors will still be unlocked and the boss will still be defeated whenever you go through the dungeon again.
The Red Clothes will make your attacks twice as strong, and when you hit enemies, they are thrown back. In other words, it acts just like a Piece of Power, but it is permanent. It doesn't make you walk more quickly the way that a Piece of Power does, though.
The Blue Clothes will double your defense, just like a Guardian Acorn, except that the effect is permanent.
As mentioned before, if you want to switch clothes, go to the end of the Color Dungeon again. But, in the Game Boy version, you can never go back to the Green Clothes.