Assassin's Creed Black Flag Resynced Guide | All Ultimate Ship Upgrades

Here’s a guide on how you can get all the Ultimate Ship Upgrades in Assassin's Creed Black Flag.

Game Guide by Ragib Rawnak on Jul 12, 2026

You can completely change how you play Assassin's Creed Black Flag Resynced by tracking down the right Gear Upgrades.

These items reduce your time spent gathering Crafting Resources and keep you looking sharp on the ocean. From Legendary Outfits and weapons to Ghostly Crew upgrades, this Guide covers the items you should locate.

Note that all underwater shipwrecks and cave systems require the Diving Bell to access. This tool unlocks during Sequence 6, Memory 1 in the story mission Diving for Medicines.

Once you collect the blueprints, you can install them at the Harbourmaster on Great Inagua or directly from the upgrade table inside the captain's cabin on the Jackdaw in Assassin's Creed Black Flag.

Mortar Storage Upgrade

This upgrade grants the maximum ammunition capacity for your long-range mortars. First, travel to Tortuga to collect the Treasure Map. Open your codex to read the clues, which point you toward Matanzas.

Dock your ship at Matanzas and navigate through the settlement. You can eliminate the patrolling guards or use stealth to bypass them.

Look for the running stream, follow the water flow up the rocks, and step behind the hidden waterfall. Interact with the patch of ground to dig up the Mortar Storage Ultimate Plan along with a bonus of 3,000 Gold Coins.

Fire Barrel Storage Upgrade

This blueprint increases your total deployment capacity for fire barrels. Travel to the Petite Caverne and search the dry paths to claim the Treasure Map in Assassin's Creed Black Flag.

The map features the specific coordinates (343, 814), which direct you to the island of Tulum on the far east side of the map.

Fast travel to the Tulum viewpoint and dive straight down into the water. Head past the shore toward the coordinates marked on your map to locate the dig site and claim the storage plan.

Heavy Shot Storage Upgrade

This storage blueprint increases your maximum carrying capacity for heavy shot broadside ammunition. First, travel to Cayman Sound to secure the Treasure Map. Open the map in your codex to see the target coordinates (863, 235), which point directly back to the Petite Caverne.

Fast travel back to the Petite Caverne to save travel time. Head past the internal waterfall landmark, turn around, and dig into the sandy floor to recover the Heavy Shot Storage Ultimate Plan.

Ultimate Mortar Upgrade

This upgrade maximizes the base damage output of your mortars. Travel to the coordinates for the Antocha Wreck. Drop your Diving Bell into the ocean and swim down to the floor. While navigating the target area, look for a large treasure chest resting on the seabed.

Opening this chest grants you the Mortar Ultimate Plan. The surrounding smaller chests hold standard gold pouches, allowing you to farm between 5,000 and 10,000 coins while exploring the wreck in Assassin's Creed Black Flag.

Ultimate Fire Barrel Upgrade

This upgrade maximizes the explosive power of the fire barrels dropped from the rear of your ship. Travel to the ruins of Santanillas to collect the Treasure Map.

Open your codex to read the coordinate markings (455, 462), which guide you toward the underwater cave system at San Juan.

Head underwater and find the cave’s entrance. If you can’t find it, follow the trail of glowing jellyfish. Swim through the flooded tunnels and reach the dry land at the back of the cave in Assassin’s Creed Black Flag.

Look for columns of rising air bubbles along the floor, which mark hidden air pockets where you can surface to replenish your oxygen meter. Eliminate the guards waiting on the interior shoreline, then dig into the earth to secure the Fire Barrel Strength Ultimate Plan.

Ultimate Heavy Shot Upgrade

This upgrade maximizes the impact damage of your close-range heavy shot volleys. Inside Ambergris Key's inner chambers you will find the Treasure Map.

Be wary of hostile enemy groups patrolling the hallways. The map is located at the very end of the main corridor.

Open the document and find the coordinates that lead to Misteriosa. Travel to the Misteriosa viewpoint, turn around, and walk into the patch of long grass on your left. Dig into the soil within the grass boundary to claim the Heavy Shot Strength Ultimate Plan.

Ultimate Battering Ram Upgrade

This upgrade allows you to destroy smaller enemy ships instantly with a single forward collision. Sail to the far northeast sector of the World Map to locate the La Concepcion Wreck. Deploy your Diving Bell and review the specific underwater map layout provided for the zone.

Swim past the patrolling sharks and search the ocean floor for the large treasure chest to claim the Ram Ultimate Plan in Assassin's Creed Black Flag.

Ultimate Broadside Cannons Upgrade

This upgrade installs additional physical cannon barrels onto the port and starboard sides of your hull, drastically increasing your broadside volley power. Set sail for the Blue Hole dive site. Drop down into the deep trenches and look for the large sunken warship along the floor.

Use the oxygen barrels scattered along the path to maintain your air meter, avoid the sharks patrolling the reef sections, and loot the surrounding gold chests.

Swim into the main hull section of the wreck to find the large treasure chest containing the Broadside Cannons Ultimate Plan.

Ultimate Swivel Guns Upgrade

This upgrade maximizes the target lock speed and explosive impact of your precise swivel guns. Travel to the Devil's Eye Caverns dive spot. This zone takes place entirely inside a closed underwater cave network with no oxygen barrels available in Assassin's Creed Black Flag.

Open your map and navigate up the main tunnel, take a sharp left turn, and push through to the end room. Open the large chest waiting at the back of the chamber to collect the Swivel Guns Ultimate Plan.

Ultimate Round Shot Upgrade

This upgrade maximizes the damage of your standard broadside round shot volleys. Travel to the specific map coordinates (738, 120). Dive down below the surface to find a flooded Mayan architectural site.

Swim past the stone pillars, enter the main cave mouth, and locate the large chest resting directly next to the central stone ruin to recover the Round Shot Strength Ultimate Plan in Assassin's Creed Black Flag.

Ultimate Hull Armor Upgrade

This upgrade maximizes your ship's health pool, allowing you to survive the devastating broadside attacks and ramming maneuvers used by high-tier Legendary Ships. Travel to the San Ignacio Wreck located at the map coordinates (348, 745) in Assassin's Creed Black Flag.

You visit this exact location as a mandatory segment of the main story mission Diving for Medicines. If you opened every container during that sequence, you will already have this item in your inventory.

If you missed it, return to the wreck, dive to the ocean floor while avoiding the sharks, and search the central wreckage path to open the large chest containing the Hull Armor Ultimate Plan in Assassin's Creed Black Flag.

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