This page explains how to find the four Great Fairy Fountains and unlock each one to get armor upgrades from Cotera, Kaysa, Mija, and Tera.
Overview
There are four Great Fairy Fountains hidden in Hyrule. Their locations are listed below. The Great Fairies can upgrade your armor to increase their defensive power. Some armor sets also give set bonuses after you have upgraded all three parts of the set at least once.
To open each Great Fairy Fountain, you will need rupees. To open the first fountain, it costs 100 rupees. To open the next, it costs 500 rupees. The next costs 1000 rupees, and the final one costs 10000 rupees, for a total of 11600 rupees to open all four.
Each time you open another Great Fairy Fountain, all of the Great Fairies become able to upgrade your armor by another level. For example, when you have opened two Great Fairy Fountains, you can go to any of the two Great Fairies to upgrade your armor to level 2, and when you have opened all four Great Fairy Fountains, you can go to any of the fairies to upgrade your armor to the maximum level.
How to Find Great Fairy Cotera
Follow the steps on the Seek Out Impa page to reach the Ta'loh Naeg Shrine. Then go east from the shrine into the forest, and look north to see a big green plant. Walk onto the orange mushrooms in front of the plant and check on it. A voice inside the plant asks for rupees. Give the requested number of rupees, and Great Fairy Cotera will appear. Talk to her to upgrade your armor.
How to Find Great Fairy Kaysa
Go east from Shae Loya Shrine and cross the Tabantha Great Bridge. Then on the other side of the bridge, climb the hills to the north and go northwest to find a big green plant. Alternatively, you can see the big green plant if you go to the top of Tabantha Tower and look south.
Go to the plant, then walk onto the orange mushrooms in front of it and check on it. A voice inside the plant asks for rupees. Give the requested number of rupees, and Great Fairy Kaysa will appear. Talk to her to upgrade your armor.
How to Find Great Fairy Mija
You might want to activate Akkala Tower before you try to find this Great Fairy. East of Akkala Tower, you will find Lake Akkala. Go into the small forest east of Lake Akkala to find a big green plant.
Go to the plant, then walk onto the orange mushrooms in front of it and check on it. A voice inside the plant asks for rupees. Give the requested number of rupees, and Great Fairy Mija will appear. Talk to her to upgrade your armor.
How to Find Great Fairy Tera
Follow the steps on Reach Gerudo Town to go to Gerudo Desert. Once in Gerudo Desert, go to the southwest corner. You will need protection from extreme heat and extreme cold. You will find the Gerudo Great Skeleton near the southwest corner of the desert. Inside, you will find a big green plant.
Go to the plant, then walk onto the orange mushrooms in front of it and check on it. A voice inside the plant asks for rupees. Give the requested number of rupees, and Great Fairy Tera will appear. Talk to her to upgrade your armor.