Treasure Map Topic

[Naberrie]

How do you gather treasure maps exactly? Like you'll just be harvesting and instead of the item you'll get a map?

I don't know about FSH, but on MNR or BTN when gathering you'll see a bottle icon and an item name that is some sort of Timeworn map. There are multiple types it could be.

Once you've gathered it, provided you've finished the Decipher quest, it will reveal the location of the treasure.