After you completed the Forbidden Forest, most of the Koroks flew to different islands in the Great Sea to check on the baby deku trees. All of them are withered and wilting. Link can bring them back to health with the help of some forest water. Here is how.
How to Water the Wilting Deku Trees
In the Forest Haven, you can collect some water in a bottle. This water is special forest water with magical healing properties. However, 20 minutes after you collect the water, it turns back into plain old water with no magical powers.
Your task is to go around to the withered baby deku trees and pour the forest water on them before the water turns back into regular water. If you succeed, you will receive a piece of heart. If you don't make it in time, the trees will wilt again and you will have to try again.
You will have an unlimited supply of the forest water, at least until it turns back into regular water, so if you accidentally pour it out on the wrong spot, you can just try again.
The Path to the Deku Tree Sprouts
Here is how I recommend watering all of the trees.
First, warp to the Forest Haven and set the wind to east. Go inside of the Forest Haven and use an empty bottle to get some forest water from the inner area (the water outside is just normal water.) Run outside, let the waterfalls take you down, get into your boat, and sail one square east to Cliff Plateau.
- At Cliff Plateau, jump into the hole and go over the platforms to reach the sparkly light on the other side. Just be patient and try not to get hurt. Water the tree outside.
- Warp to Southern Fairy Island, set the wind to west, then sail west to Shark Island and water the tree there.
- Warp to the Tower of the Gods, set the wind to south, sail to the Private Oasis, and water the tree there.
- Warp to the Tower of the Gods again, and this time set the wind to north, then sail to Eastern Fairy Island and water the tree there.
- Warp to Greatfish Isle, stop the boat near the spiral island, then walk up and water the tree there.
- From Greatfish Isle, set the wind to southwest, sail to Needle Rock, and water the tree there.
- Warp to Tingle Island, set the wind to northwest, sail to Mother & Child Isles, and water the tree there.
- Finally, from Mother & Child Isles, set the wind to north, sail to Star Island, and water the tree to get the heart container.