After Jiahto deciphers the stone tablet that you help repair, you must consult with King Dorephan.
This quest begins after you complete The Broken Slate.
Learn King Dorephan's Whereabouts
Go back down to Zora's Domain and you can ask people where King Dorephan went. The kids in the throne room mention a secret hiding place. Go around the north side of the throne room and sneak into the water just north of the kids. Approach them and press the button to listen.
Restore the Zora Armor
If you haven't completed Restoring the Zora Armor, and if you don't have an Ancient Arowana fish, you should teleport back to the shrine at Mipha Court, where you talked to Sidon earlier. You can go southwest to the statue of Mipha. You will find some Ancient Arowana swimming around the statue. Catch one.
Talk to Yona
Now that you have an Ancient Arowana, go back to Zora's Domain and talk to Yona in the infirmary, which is beneath the throne room. You will receive the Zora Armor, which will allow you to swim up waterfalls.
Go to Mikau Lake
Go northeast from Zora's Domain and go up the eastern waterfall in the clear water. You will reach Mikau Lake. Go to the waterfall that is falling into Mikau Lake, and go through this waterfall by using the Zora Armor to dash. You will find the Pristine Sanctum. Inside the cave, use the Zora Armor to go up the waterfall, then talk to King Dorephan. You will get five King's Scales.
Find the Watery Bridge
You can talk to Sidon to tell him the news from the King. After that, you must find the "watery bridge" mentioned on the stone tablet that Jiahto deciphered. You can find it by standing on the "land of the sky fish" and shooting an arrow with a King's Scale through a "droplet".
You can look east from Mipha Court to see a waterfall that is brown, but not full of sludge, so you can glide east from here and use the Zora Armor to swim up it.
Find the Droplet
This island is surrounded by floating rocks. The stone tablet said "among the floating rocks you see, a droplet waits for you". First, go to the highest point of the island and throw Splash Fruit to wash away the sludge there. Then stand on the southwest edge of this platform and look southwest. If you are standing in the correct spot (coordinates ) and looking southwest, you will find the droplet. Attach a King's Scale to an arrow and shoot it through this droplet. (If you need more King's Scales, go back to the Pristine Sanctum and talk to the king.) This completes the quest Clues to the Sky. You can now talk to Sidon to let him know what you discovered.