Okay, by now, you should have all eight Triforce Charts. If not, return to the section above all collect them.
At some point in your quest, probably on your first visit to Windfall Island WAAAY back, you’ve probably rescued Tingle from the Windfall jail. Once you have, you will need to collect a total of 3184 Rupees ; no more than that is required.
If you have stocks of spoils, you can sell them. You can also try to get treasure from the Treasure Charts and light rings on the sea. Once you have done this as well, use the Ballad of Gales to teleport to shudder Tingle Island.
Okay, get onto the island and defeat the Blue Chuchu there for its jelly if you have not done so at any point in the game. Now, on the island, you’ll find a ladder. Climb up it and you’ll find Tingle on the platform.
Talk to him and he’ll (eventually) offer to decipher the Triforce Charts… for 398 Rupees a piece! (After all that trouble to save him, too…) Give him the cash and he’ll use some of his “magic” to make the map readable. Do this seven more times to decipher all the maps (and empty your wallet).
In all eight cases, you’ll find a Triforce Shard. The charts correspond to these areas:
Triforce Chart #1: Greatfish Isle.
Triforce Chart #2: Gale Isle.
Triforce Chart #3: Stone Watcher Island; it’ll help to sink the cannon boats before trying for the shard.
Triforce Chart #4: Outset Island.
Triforce Chart #5: Cliff Plateau Isles.
Triforce Chart #6: Southern Triangle Isle; it’ll help greatly if you kill a majority of the nearby Seahat population.
Triforce Chart #7: Seven-Star Isles; be prepared to fight some Kargarocs.
Triforce Chart #8: Two-Eye Reef (G4); you’ll have to clear out the cannons first. Also get the magic upgrade while here!
Once you have all eight pieces of the Triforce, they fuse together to form the final piece of the Triforce, the one that the Hero of Time once had possession of: the Triforce of Courage. After congratulating you, the King of Red Lions urges you to hurry back to Hyrule; use the Ballad of Gales to teleport to the Tower of the Gods, but ONLY once you’ve become prepared.