Assassin's Creed Black Flag Resynced Guide | How to Get Mortar Storage Ultimate Plan

Here’s a guide on how to get the Mortar Storage Ultimate Plan in Assassin's Creed Black Flag Resynced.

Game Guide by Ragib Rawnak on Jul 22, 2026

It takes some time to get the Jackdaw to its full potential, but the Mortar Storage Ultimate Plan means maximum firepower during the high-seas battles.

If you want to bombard the enemy frigates and legendary ships with heavy explosive shells without running out of ammo all the time, this upgrade is a must.

You need to find a specific treasure map and dig the buried chest to craft this final mortar capacity upgrade. Here is the exact path to get it done.

Find the Treasure Map in Tortuga

Before you can dig up the blueprint you’ll need the treasure map to know where it is buried. Head to Tortuga at coordinates (851, 1352) in your ship to start the journey in Assassin's Creed Black Flag Resynced.

When you arrive, make your way to the northeast side of the island, right on the coast. On the beach you will find a small rowboat beside a palm tree. Between the boat and the tree, a corpse lies on the sand.

Search the body to pick up the treasure map. After you have the map safely in your inventory you may go to where the actual chest is located.

Dig Up the Blueprint at Matanzas

The treasure map will lead you straight to a hidden location at coordinates (312, 617) near Matanzas. Fast-travel or sail to Matanzas and anchor down near the shore.

Locate the rowboat docked inside the small cove then walk south directly into the forest area surrounding it in Assassin's Creed Black Flag Resynced.

Keep going until you reach a large stone statue next to a waterfall. Walk directly behind the falling water and interact with the ground to dig up the buried chest.

Inside, you will receive the Mortar Storage Ultimate Plan upgrade alongside a sum of Reales.

Once you possess the design plan, open your ship upgrade menu while aboard the Jackdaw or visit any local Harbourmaster.

As long as you have the required resources and currency, you can craft the upgrade immediately and start carrying maximum mortar rounds on the high seas in Assassin's Creed Black Flag Resynced.

FAQ

Q. Do I need to buy the treasure map from a store?

A. No, you cannot purchase this map from a General Store. You must manually loot the corpse on the shore of Tortuga at coordinates (851, 1352) to trigger the chest spawn point.

Q. Can I dig up the chest at Matanzas without finding the map first?

A. No. Buried Chests in Assassin's Creed Black Flag Resynced will not appear as a dig prompt until you have picked up the corresponding treasure map.

Q. Is this the same as the Mortars Ultimate Plan?

A. No. The Mortar Storage Ultimate Plan increases your ammo capacity, whereas the Mortars Ultimate Plan upgrades the mortar power itself and is found at the Antocha Wreck underwater dive spot.

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