Inside Ganon's Castle
Requirements: Six Sages' Medallions, Light Arrows. Enhanced Life and Magic Meters are recommended.
Hints:
DESTROYING THE BARRIERS
The first room Inside Ganon's Castle has two Beamos near the door leading to the main room: just ignore them and go on your merry way. When you enter the main room, you'll see the large pillar in the centre, which is the only entrance to Ganon's Tower. If you look around, you'll see the six energy waves feeding the main barrier. Infiltrate each room and destroy the barrier as you wish, but make sure you have the necessary items to reach the barrier in the first place.
Oh, and here's another helpful piece of advice: see that bridge that's right in front of you when you first enter the main room? Just under it is a fake wall which can be revealed with the Lens of Truth. In here are some fairies and Business Scrubs with Arrows, Bombs and Life and Magic potions!
FOREST BARRIER
WATER BARRIER
SHADOW BARRIER
FIRE BARRIER
LIGHT BARRIER
SPIRIT BARRIER
ACCESS GRANTED
Requirements: Din's Fire, Fire Arrows, Hookshot, Hover Boots, Bombs. The Song of Time and the Iron Boots are recommended.
When you first enter the room, walk around and you'll come to a series of unlit torches. Get close enough to one and you'll encounter a Wolfos. Get rid of him and stand in the centre of the circle of torches, then use Din's Fire to ignite them all. Now ready a Fire Arrow and aim above the blocked door to open it.
In the next room, you must use your Hover Boots and fans to cross gaps to collect all the Silver Rupees. There's a Time Block hidden near the entrance which can help you get into position, and don't forget to send the Beamos statue flying to make this room a lot easier. A switch is also there which reveals a Hookshot target, and allows access to one Silver Rupee.
The next room you enter will have the barrier's core. Fire a Light Arrow into the core to destroy the barrier, and Saria will return you to the main room.
Requirements: Hammer, one empty bottle or Blue Fire.
In the centre of this first room is a Blue Fire torch. Your first priority is destroying all the Freezards while avoiding the falling stalagtites. That done, use Blue Fire to melt the Red Ice around the next door. Make sure you have at least one bottle of Blue Fire before proceeding.
In the next room, you'll find two blocks which you have to push around to reach the right place. First of all, go to the block furthest from you and push it into the gap in the floor. Now use the other block to reach the high ledge. Activate the switch with the Hammer and enter the door, using Blue Fire to remove any obstructions. If you stuff this one up, simply leave the room and re-enter to reset the blocks and timer.
You'll now be at the Water Barrier core, so fire a Light Arrow to dispel it and for Ruto to return you to the main area.
Requirements: Fire Arrows, Longshot, Lens of Truth. The Mirror Shield is recommended.
This room is a over a bottomless pit, but use Fire Arrows to ignite the torch at the right of the room and reveal some blocks. Work your way to the platform with the Like Like before the timer ends, being wary to avoid getting caught by the Like Like or when he swallows you, he'll more than likely throw you into the pit! If he captures any equipment and you're thrown into the pit, you'll have to fork out cash to get it back, so equip the Kokiri Tunic and Mirror Shield to make Like Like starve.
Once you're on Like Like's platform safe and sound, get rid of him and ignite the torch again. This time, jump down the blocks leading down and step on the switch to reveal a chest. Turn around and use the Longshot to grapple the chest and return to the Like Like platform, then open the chest to obtain the Golden Gauntlets.
Once you have your treasure, use the Lens of Truth to reveal a hidden walkway leading to the switch that opens the door. Once the switch is down, use the Longshot to grapple the torch near the door. You will now be at the core of the barrier, so fire that Light Arrow to get rid of it! Impa will warp you back to the main room.
Requirements: Goron Tunic, Hover Boots, Golden Gauntlets, Longshot.
Equip the Goron Tunic to survive in the intense heat of this room, and use the Hover Boots not only to cross the instant-death lava but also to prevent the central path from sinking (isn't that nice?).
Gather the first Silver Rupee you see on the right of the sinking path, then head towards the left. There's one near the rotating flame thrower, and another under the large pillar; lift it with the Golden Gauntlets, which also creates a path to another Silver Rupee. However, make sure you have all other Rupees before attempting to gain the one near where the large pillar lands, because as far as I can tell you can't get it without falling into the lava. Since you gained it, the door will still be open when the room resets, but not if you don't have all five!
Once the door is open, use the Longshot to reach the door and enter to get to the Fire Barrier's core. Fire the Light Arrow to dispel it, and Darunia returns you to the main room so you can enjoy its destruction live!
Requirements: Golden Gauntlets, Hookshot, Zelda's Lullaby,
The entrance to the passage leading to this barrier's core is hidden by a large silver pillar between the entrance to the Fire and Spirit Barrier passages. Lift up the obstructing pillar with the Golden Gauntlets, and Link will toss the pillar at the active barrier surrounding the entrance to Ganon's Tower, smashing it to pieces. You can now access the Light Barrier's passages.
In the first room, you must destroy all the hostiles. Unfortunately, they are only visible with the Lens of Truth. However, you don't need to use the Lens to make the enemies visible; just walk around and when Navi turns yellow, lock onto the hostile with Z-Targeting, which will enable you to know where you should aim your attacks. Once this is done, a new chest will appear containing the key. Open the other chests if you wish, but remember that some of them are trapped. In the next room, you simply need to play Zelda's Lullaby on the Triforce symbol to make the chest with the key fall from the roof.
In the third room, you must obtain all of the Silver Rupees while avoiding the rolling boulders. Some Rupees are hidden along the outer edge of the room, others near the central shape. There is another one atop the central shape which you must obtain by using the Hookshot.
When you enter the next room, walk straight through the fake wall to avoid the Wallmaster and you'll come to the core of the Light Barrier. Use a Light Arrow to dispel the barrier, and Rauru will return you to the main area.
Requirements: Bombs, Hookshot, Fire Arrows, Mirror Shield, Bombchus. The Flame Spin is preferred.
In the first room you must move the Armos Statues to make the switchblades move away from the Silver Rupees. There is another one above the Beamos, which is gained using the Hookshot.
Defeat all the Torch Slugs in the next room to give yourself room to move. Now use a Bombchu to activate the distant Crystal Switch, between the two torches. If you like, use the Flame Spin on the closer switch to reveal a chest with 10 Bombchus.
In the next room, use the Fire Arrows to burn away part of the roof, then use the Mirror Shield to reflect the light onto the Sun Switch. Tripping the wrong switch reveals Wallmasters, so find the right one by facing the entrance to the room, then triping the Switch on the right of the door.
In the next room is the Spirit Barrier, which is dispelled by firing a Light Arrow into its core before Nabooru warps you back to the main area.
Once all six barriers are sabotaged, the main barrier around the entrance to Ganon's Castle is dispelled. You can now cross the bridge near the original entrance and enter Ganon's Tower.