Have you heard of Angoya Island's antique merchant Stony?
South Sea pirates stole his cherished antiques a while ago. They took something called 'Cup of Groanda.'
The Fort Quartermaster hides away most of the objects stolen by pirates. You should find him near Southern Island's South Sea Fortress.
Once you get the antique, give it to Stony. He'll reward you handsomely.
Red Coconut City is to the south of Angoya Island. It can be reached by boarding a ship here, he informed you.