Assassin's Creed IV: Black Flag - PS4 - Final Buried Treasure - 100% Sync Achieved (Blind)

My final treasure map was a reward for one of the Kenway's Fleet trades. It's the trade "Great Reputation II". Reaching that particular trade can take a while, as it's one of the final ones to unlock. After that, you still have to wait a long time for the trade to complete.
When I head up to the hideout to get the map I think at least two actual days had passed since unlocking that trade. I have a final look around the hideout before getting the map, checking out some of the items I'd unlocked. If you just want to see the map being acquired skip here 12:46, bear in mind those map co-ordinates won't reveal anything unless you have the map itself, so don't bother going for the chest without it. The treasure was in the underwater smuggler's den, Anotto Bay. After finding it I return to the Jackdaw and check out my 100% completed progress tracker, ah the satisfaction.
Since beating this I've also 100% synced Unity and Syndicate, so will upload them at some point. Those have even more content than this.