Legends speak of the sword that seals the darkness, hidden deep in a forest.
Find the Forest
After activating Woodland Tower, float northeast from the tower to land in the forested road. Follow the road north and you will find yourself in the Lost Woods.
You will see a torch up ahead. There is a correct path through the forest, and if you do not follow the correct path, the mists will swirl around you, and you will be sent back to the entrance of the Lost Woods. But if you run back to the correct path in time, the mist will recede, and you won't get kicked out. The wind always blows in the direction that you are supposed to go, so follow the sparks from each torch that you encounter.
Eventually, you reach two torches, and a handheld torch. Take the handheld torch and light it. From now on, you will have to follow the sparks from your own torch. You can also watch the grass and the small blue lights that float in the air to check the wind direction. Be sure to go slowly and stop often to check if the wind direction changes.
If you are near a wall or other obstacle, try to move away from it. Being too close to a wall can cause you to get kicked out of the forest even if you are going the right way.
Eventually you will see pink petals on the ground and a hollow log ahead. Go through the hollow log to reach Korok Forest.
Go northwest into the forest and you will see the sword in the pedestal. Go up to the sword and press A. There will be a cut scene.
After this, if you have at least 13 full hearts (yellow bonus hearts from food don't count), then you can pull the Master Sword from the pedestal. You won't die if you try to pull it with fewer hearts; the Deku Tree will stop you.
If you don't have enough hearts, visit the Keo Ruug Shrine in this area so you can warp back here after you have gotten enough heart containers.