Treasure Note
The Treasure Note is a Quest item found in Golden Sun: Dark Dawn. It can be obtained after the Grave Eclipse has been activated. It gives a hint on how to get aboard the Lost Ship.
Obtaining the Note
If the party chooses to revisit Ayuthay during the Grave Eclipse, they will be informed that Ku-Tsung and Ku-Embra have escaped the prison. Going to the ancient tree where the Tree Flute was used, the corpses of the generals will be seen, and using Spirit Sense on either corpse will trigger a conversation about a map which they hid in Kaocho.
Head to Kaocho Palace, and use Grip on the left pole. Going to the left and checking the cracked wall will give you the Treasure Note.
The note reads as follows:
This shows a pirate treasure's location. Coming from the south, go west when you reach a reef shaped like a hand.