Assassin's Creed Black Flag Resynced Guide | How to Get Elite Harpoon Upgrade

Here’s a guide on how you can get an Elite Harpoon Upgrade early on in Assassin's Creed Black Flag Resynced.

Game Guide by Ragib Rawnak on Jul 11, 2026

For you to make the most of your sea hunting power in Assassin’s Creed Black Flag Resynced, you’ll need to find the Harpoon Strength Ultimate Plan.

It is important to upgrade this gear if you want to be able to take down the toughest sea creatures. This Naval Guide walks you through the exact steps to locate the buried design and complete the final upgrade.

Find the Treasure Map at Mariguana Island

Your hunt begins at Mariguana Island. Head over to this location and look around to find a certain treasure chest in Assassin’s Creed Black Flag Resynced.

Unlock this chest to uncover a secret map. Now, this map doesn't actually give you the upgrade, but it gives you the exact clues and coordinates to find the ultimate burial site.

Set Course for Andreas Island

Look at the map you just picked up; it will direct you to Andreas Island. Go to that location, go to the beach area near the watchtower, and then look at the exact spot of ground shown on the map.

Interact with the dig site to discover a buried chest containing the Harpoon Strength Ultimate Plan in Assassin’s Creed Black Flag Resynced.

Complete the Max Upgrade

Once you have the design plan, return to your home base at Great Inagua and visit the Harbourmaster building near the docks. You can also complete this upgrade at the upgrade table inside the captain's cabin on the Jackdaw.

The final tier costs 4,000 Gold Coins to craft. Upgrading to the max level increases your base harpoon damage from 20 to 30, giving you the extra firepower needed to successfully hunt any apex creature in the ocean in Assassin's Creed Black Flag Resynced.

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