How to Get Past Gerudo's Fortress in Ocarina of Time

Use your long shot (or hook shot) device to cross the broken bridge into Gerundo territory. Your horse Epona can also jump across.

Watch for when a Gerundo guard soon finds you and locks you in a cell. Use your long shot on a wooden plank above your head to escape and proceed to the first door on the far-left of the fortress. Avoid the Gerundo guards or fight them or they'll keep locking you in a cell. You can use this way to escape when they do.

Notice that two carpenters that are also prisoners of the Gerundo are in this cell on the far left. Talk to one of the two carpenters that are being held in the wooden cells until he says, "Watch out!" This is a signal that the Gerundo guard will attack you. Fight and defeat her and she will drop a key. Use this to free the carpenters and proceed through the door on the north side. Do not go out the way that you came.

Hide from the guards in the mess hall and sneak out the door on the right. You will find yourself back outside. Use the long shot or your bow to stun the guard. There will be another locked door behind her, an imprisoned carpenter and a Gerundo thief with a key. After you are done with them do not go out the way you came. Continue proceeding north.

Crawl down the ivy that should be right in front of you. Go through the door that you find. Here you will find another Gerundo guard and carpenter number 3. Return to the mess hall after freeing the carpenter.

Bypass the whole mess hall by using your long shot on one of the wooden ceiling planks. You should fly right over the room and be back near the entrance. To the immediate right of this entrance should be a small ledge. Drop down to this ledge and you will see a door partly obscured by crates. Don't enter the room until you have stunned the guard inside using your bow or hook shot. Be patient and you will see her walk past the door.

Free the fourth and last carpenter, and another Gerundo guard will appear. She will not attack you, but instead will give you the Gerundo Membership Card that will enable you to walk freely in the fortress.