How to Get the Biggoron Sword
1.) So you start out with the blue cucco, Cojiro. Go to the Lost Woods. As you turn into the left tunnel, Cojiro will crow again! Look in there and you'll see the guy that used to hang out under the tree at the Kakariko at nights. That's the Cucco Lady's brother? Must be, because Cojiro knows him! Offer Cojiro to him and he'll go on about how Cojiro only likes nice guys, so you must be a nice guy. Then he starts begging you to bring something to the potion shop in the Kakariko. Say yes, and you have three minutes to get it back to the Kakariko. Don't worry, you have Epona, so it'll be quick. So, go on back to the Kakariko Village.
2.) Now go up the two sets of stairs to the left of the entrance and there's a house that's been turned into a potion shop. But this isn't the one the dudes was talking about. Go in the shop and look towards the left and you'll see an opening to the back. Now, go down the ladder, up the stairs and into this house. Inside is a freaky lookin old lady, offer her the mushroom. She, in return, will give you some odd potion. Go give it back to the dude in the Lost Woods! (But remember! Now, you can buy the Ultimate Potion from her. It's a blue potion that will not only fill up your hearts, but also your magic meter. It'll come in very handy.)
3.) When you get back to the Lost Woods, you'll see that the dude is gone, and a little Kokiri girl is there. Offer her the potion and she'll give you the Poacher's Saw that the dude left there. Now let's go into uncharted territory: Gerudo Valley!
4.) To get to Gerudo Valley, exit the Kokiri Forest, then just follow the walls to the left. Along the way you'll see a bunch of gates and fences. This is the formal entrance to Hyrule Lake. Well, keep going and you'll see a bunch of dirt and boulders. Just keep following the wall and you should end up in Gerudo Valley. Now, when the game does on overall view of the place, you may notice that the bridge across the river is broken... This is going to be fun. :) Line Epona up so that she's about to go down the stairs. Now back her up, give her a few carrots, and she should fly over the river! Now notice a tent and a little dude beside it. It's the carpenter from the Kakariko Village when you were younger! Offer him the Poacher's Saw. He'll take it and give you a Broken Biggoron's Sword! So go on now to the top of Death Mountain.
5.) When you get to the top of Death Mountain, go to the right. Then Biggoron will stand up, rubbing his eyes. Now, this is a BIG Goron! Offer him the broken Biggoron sword, and he'll take it in exchange for his prescription. You are to go down to King Zora in Zora's Domain to get Biggoron some eyedrops. So go on to Zora's Domain.
6.) When you get to Zora's Domain, you'll see that it's all frozen over! But head to where King Zora's throne is and you'll see that King Zora is in some kind of red ice. To get rid of this, you need blue fire. You can buy it at a potion shop for 300 rupees, but you need a Giant's wallet just to hold that much. Or you can go into the Ice Caverns to find some. Unfreeze him and show him the prescription. He'll tell you that he can't make it, but he has the ingredients. He'll give an eyeball frog. (A frog with, as you can imagine, very large eyes. LoL) He'll tell you to take it to the laboratory at Lake Hylia, but again you have to hurry because you're timed. And for those of you who already know the Serenade of Water, don't use it, you're time will be cut too short. So, head over to Lake Hylia's Labortory.
7.) Go inside the laboratory and talk to the funky little dude inside. Then present him with the eyeball frog. He'll get all excited thinking it's a present from you and he's gonna make fried eyeballs for dinner! Yuck!! >:P Anyway, you'll have to correct him and tell him it's for eye drops. He's a bit disappointed, but he'll live and make you the eye drops. But again, you'll have to rush them to Biggoron because the eye drops have no preservatives.
8.) Drive Epona QUICKLY back to the Kakariko Village. Then roll your way up the mountain! Yes, roll. I find that you go faster if you press the attack button repeatedly. And if you planted a magic bean by the entrance to Dodongo's Cavern, it'll be much quicker. Anyway, Mr. Biggoron Person will be VERY happy to get his eyedrops. He'll take them, very loudly. Then he'll give you a Claim Check for your sword. You'll have to wait a few days until it's ready. You can pass time by playing the Sun's Song, or you can go on with your Temple conquering. After awhile, go back to Biggoron and give him your Claim Check. If it's not ready, he'll say so, if it is, he'll give you your brand new Biggoron Sword! YAY!! It's bigger and does more damage than the Master Sword, and it won't break like the Giant's Sword. But since it's so big, you'll have to use both hands. Meaning, you can't use your shield correctly without having to stop and put the Sword back. So I shall leave you with this. Use your Biggoron's Sword respectfully. Have fun! :)