The Fire Arrow is a new upgrade of Link’s bow in The Legend of Zelda: Ocarina of Time. But you can only obtain this increased weapon once a dungeon has been completed as Adult Link. After completing the Water Temple, go to Lake Hylia and carry out a brief task that allows you to acquire this item. Here’s what you need to do.
Complete the Water Temple

Completing the Water Temple as Adult Link is a prerequisite before acquiring the Fire Arrow. The item can be obtained after completing that dungeon but heading to Lake Hylia after finishing the dungeon is the best option.
How to Obtain the Fire Arrow at Lake Hylia

After you have finished your quest in the Water Temple, go straight to Lake Hylia. You have to shoot the sun with an arrow to create the Fire Arrow.

If you arrive there and it’s not dawn yet, play the Sun’s Song to progress to a new day. Then shoot the arrow when the sun rises. It’s important to do it during dawn; shooting during some other time will not work. Once you shoot the arrow, the Fire Arrow will land on the platform near Lake Hylia. Go and grab it.
Once you have the Fire Arrow, you can equip it and switch between it and your regular arrows whenever needed. If you miss the opportunity to collect it, you can always return to Lake Hylia and try again, as long as you have completed the Water Temple.

