The Legend of Zelda: A Link to the Past/Death Mountain
You first discover how to travel between the Dark and Light Worlds when you reach the summit of Death Mountain. There, you will come upon a mysterious tile that glimmers in the light. Step on it to discover its mysterious properties.
 The Western Mountain
 The lonely tunnel
The sign outside the Mountain Tunnel (A) forbade travelers to pass unless they had permission from the King. Knowing that the King has been deposed by Agahnim, feel free to forge ahead, pull up the big stone that blocks the path and enter the tunnel.
The tunnel is dark, with only a small area for visibility. To go through the cave, turn east, take the south-east fork, followed by the small north path. You will then find an Old Man who needs help. After you escort him to a cave further up the mountain, he will give you the Magic Mirror. The Mirror is used for warping to the Light World from the Dark World or to the beginning of a dungeon.
 Mountain caves
The caves, long thought to be refuge for early Hyruleans, have been taken over by mountain beasts. Many of them still hold treasures and tools left by the Hyruleans when they moved to lower ground. Some of the caves were single dwellings, but others are multi-leveled networks of rooms. You should also seek refuge and treasure in the caves during your long climb to the top of Death Mountain.
 A tower of terror
Carefully make your way through the dark mountain tunnels towards the top of the mountain. Explore the many caves and ledges along the way, uncovering treasures and clues as you go. Boulders many times larger than you crash down from above. An odd formation of rocks at the top of the mountain, which looks like a pair of eyeglasses, is dubbed Spectacle Rock. It stands between the climber and the Tower of Hera, and it appears that there is no way to scale its sheer sides. When you finally climb to the high plateau near Spectacle Rock, you'll see the glimmering tile that transports you to a different, but strangely familiar, world. You will find yourself transformed as well.
 Into the darkness
When you reach the top of Death Mountain, you will discover that there is no way to reach the Tower of Hera. You will find a circle of stones surrounding a Warp Tile to the dark dimension where you will be turned into a helpless rabbit. To the left of the place where you appear in the Dark World, you will find a patch of ground that mirrors the shape of Spectacle Rock. Use the Magic Mirror there to warp back to the Light World. When you arrive, you will be able to collect a Piece of Heart. By jumping off the north side of Spectacle Rock, you can now reach the Tower of Hera.
 A Hylian Monolith
A bridge stretches from the west of the Tower of Hera to an island in the clouds. Cross the bridge after defeating a Tail Worm. You will find another Hylian Monolith that was erected by the Hylian people on a peak west of Spectacle Rock. Like the others, this Monolith is inscribed with a message in the old tongue, so only one who has the Book of Mudora can decipher it. By translating the message with the Book, it advises you to return when you have the Master Sword.
 The mysterious Moon Pearl
Legends tell of a magic Moon Pearl that allows people to retain their human forms in the Dark World. There are many tales about the location of the pearl, and one of the most persistently retold is that it lies in a chest somewhere in the Tower of Hera. Sahasrahla will send you a telepathic message urging you to find the famous pearl.
 The Eastern Mountain
 Caves found in the crags
A portion of the bridge that leads to the eastern peak had long ago washed out, making it impossible for anyone to explore that area. You will eventually discover a way to cross the gaping hole in the bridge. When you reach the other side, you will discover another system of caves and tunnels.
 More Dark World doors
While exploring the Death Mountain region, you will discover more tiles that you can use to travel back and forth between the Dark and Light Worlds. One is hidden under a rock, one is situated in plain sight (on the west side), and another appears only after you pound pegs into the ground.
 Tower of Hera
The multi-leveled Tower of Hera is an intimidating structure that has many block barriers controlled by Crystal Switches. It also has Star Tiles that suddenly change the floor plans, sometimes creating pits that have claimed many intruders. You enter the tower in the 2nd floor. From the grand foyer, a stairway on the left leads down, another on the right leads up to the 3rd floor and beyond. The huge Moldorm, which is not fond of guests, occupies the entire 6th floor.
 1st Floor
You do not start the Tower of Hera on the 1st floor. Instead, the entrance is found on the 2nd floor.
Your first visit to the 1st floor will take place in the lower-left hand room. Two Stalfos and a Tail Worm will be guarding a key. In order to get the key, you must hit the Crystal Switch and lower the orange blocks that surround it. But this will also free the Tail Worm in the process. Defeat all of the enemies, and collect the Small Key. Before you return to the second floor, remember to hit the switch back to blue, or you won't be able to move freely through the 2nd floor.
You will return here once you use the key you just collected to unlock the door near the map on the second floor. When you arrive, the tiles of the floor will begin to rise and attack you. You've dealt with this before, and this time is no different. If you stand in the doorway the tiles will not hit you. Simply wait until the tiles all finish then continue. You'll probably need to hit the crystal switch in the corner to lower the blue fence that blocks the door to the right.
Head through, and you'll encounter a room with three Tail Worms, two of which are located behind orange blocks. You can take them on at whatever rate you are comfortable, but you'll need to hit the orange Crystal Switch at some point to make the lower door accessible.
When you enter through, you will see two Stalfos, and four unlit torches. Destroying the Stalfos does nothing to change the room, but there is one other trick to try. If you recall, lighting all four torches was the key to completing the Desert Palace dungeon. That trick works here too. Quickly light all four torches to make a treasure chest appear. Open it up, and discover the Big Key inside. Now you have a choice. You may either return to the 2nd floor the way that you came, or take a little shortcut back to the entrance, courtesy of the Magic Mirror.
 2nd Floor
This is the floor upon which you start. You will immediately notice an arrangement of raised blue blocks and lowered orange tiles, as well as a Crystal Ball at the entrance. Blue and orange Crystal Switches are found in several Hyrulean palaces, and the Tower of Hera is no exception. The beautiful switches are the key to raising and lowering the blue and orange Switch Fences that pop up in places. When you strike the Blue Crystal Switch, all of the blue Switch Fences fall and the orange ones rise; when you strike an orange switch, the orange Switch Fences fall and the blues ones rise.
Ultimately, you'd like to go up, but before you can do that, you must visit floor 1... twice. The door at the top, next to the Map is locked, so you must first take the stairs through the door on the left and grab a key.
When you return, You need to visit the top half of the room. There is a Tail Worm and two small fire-breathing Kodondos trapped behind barriers. You can defeat them if you'd rather not have to deal with their fire breath. When it's safe, unlock the door at the top and proceed back downstairs.
Finally, when you will return to the 2nd floor once more, you may climb the stairs through the door on the right, and complete the remainder of the Tower.
 3rd Floor
You will be introduced to two new things on the third floor: Pons and Star Switches. All of the enemies on Floor 3 are the deadly Pons. They have a thick rubbery hide that causes you to bounce backwards, even when you strike them with your sword. You can hurt them and dispose of them easily enough, but you must always take care to notice what lies directly behind you, because you are sure to hit it when you strike the Pons.
When you arrive on the third floor, you will encounter three Pons, three holes, and a Crystal Switch. The Crystal Switch does not directly affect anything in this room, but it does affect the next. Make sure to leave the Switch set to the orange color before you leave. Carefully destroy the three Pons in the room. It is always safest to keep your back to the wall when trying to fight them. If you happen to fall through the floor, you will land on the floor below, and may reattempt the room as long as you have at least one heart remaining. When you defeat the three Pons, the shutter door to the left will open.
In the next room, you will see three Pons, two holes, one blue and one orange block, and a Star Switch. Depending on the state of the Crystal Switch in the previous room, one of the blocks will be raised, and the other lowered. You may find that a hole is situated in front of the block that's lowered, and you may think that your only solution is to return to the previous room to give the Switch a whack. However, if you instead step on the Star Switch, you will discover that the holes move about the floor, and that it is now the raised block which has a hole in front of it, which will allow you to pass over the lowered block to the room above.
This next room can be difficult if you are unaccustomed to dealing with Star and Crystal Switches. If you left the Crystal Switch in the orange state, this room will be substantially easier. If not, return to the third floor entrance and change the Switch. Make sure that you step on a Star Switch so that there is no hole in front of the lowered block. When you reach the opposite side of the room, hit the Switch if your access to the door is blocked by the fence.
 4th Floor
When you reach this floor, you will notice that you have a number of Tail Worms and Kodondos to deal with. Nothing is a tremendous threat, and the biggest obstacle to your crossing the floor are variously laid out jars of pottery, some of which may contain hearts. Proceed carefully down the right side of the room and to the center.
Once there, you can easily grab the Compass out of the small chest. You can also receive a message from Sahasrahla telling you to collect the Moon Pearl. Alas, the treasure chest that holds the magical item is blocked off by a hole in the floor. Even by playing with the Star Switches, all you accomplish is moving the floor holes closer or farther from the chest. No matter how you approach it, there does not appear to be any way to collect the treasure from this floor.
If you continue up to the fifth floor, you will discover many holes there, as well. By stepping on the Star Switch on the left, you can make a new hole appear above the Bumper in the middle of the room. Then, from the top side of the hole, jump down to the platform with the treasure chest and retrieve the Moon Pearl. With the Moon Pearl, you can retain your shape in the Dark World.
 5th Floor
There are four regular blue Pons here and one even stronger red Pon to deal with, in addition to the usual holes. There is also a Star Switch situated precariously next to a rotating bar of fire. As if the Pons weren't bad enough to deal with, a few Bumpers are also placed on the floor for good measure. Before you race off to the sixth floor where Moldorm awaits, there are some aspects of the floor you may wish to investigate.
The floors in the Tower of Hera are riddled with holes, and people who fall into them disappear from sight and land elsewhere in the tower. Some even report falling several floors and finding Faeries in a room that was completely sealed off, and others deliberately jump into the pits to land in places that they could reach no other way. Stepping on Star Tiles changes the position of some pits.
If you drop through the top left hole in the floor, you will fall a long way down. When you finally land, you will find yourself in a Faerie pond room. Use the Faeries to restore your power, or fill your bottles, and take the Warp Tile back to the 5th floor. This will be a big help during the battle with Moldorm on the 6th floor.
Also helpful are the jars of pottery, all full of hearts. There is no excuse not to travel up to the sixth floor with anything less than full health. When you are ready, head upstairs to fight for the final pendant.
 6th Floor
 Boss: Moldorm
Moldorm appears to be a gigantic Tail Worm. In addition to his enormous size, he also has exceptional defense. He mindlessly wanders around his den, but he likes to keep it clean. Any invader on his floor is treated the same; brushed off the edge. As a result of Moldorm's thick impenetrable skin, there is only one weak point on his body that can take damage: his tail.
As Moldorm wiggles and writhes across the floor, you must do your best to situate yourself behind him in order to strike his tail. This is no easy task, as Moldorm never holds still, and rarely travels in a straight line. He prefers to turn frequently, and his motion is hard to predict. Naturally, if you want to get through this fight fairly quickly, the biggest thing you'll want to avoid is getting pushed over the edge and down to the floor below. You will be able to return if that happens, but Moldorm will return to his full strength if you leave the room.
One effective way is to wait by the edge facing inward and wait for Moldrom to charge straight for you. This is the only time he straightenes himself. Use the pegasus boots to dash quickly, and you will go through Moldrom without getting knocked aside and pierce through his tail. Be sure to stop before you charge off the edge of the stage and face inward again. Doing this horizontally seems to be more comfortable than vertically.
Once you manage to land six blows to his tail, he will be destroyed, leaving behind a precious Heart Container. Once you collect it, the final pendant, the Pendant of Wisdom will drop from the ceiling.
 One last step
Collect the pendant as reward for the difficult fight. When you do, Sahasrahla will contact you to congratulate you on the splendid accomplishment. With all three pendants in hand, access to the Master Sword may yet be yours. But to find it, you must return to the Lost Woods, where the sword slumbers.