AC Black Flag Resynced: All Ultimate Plan ship upgrade locations

Assassin’s Creed: Black Flag Resynced allows you to sail the Caribbean, but there are plenty of naval threats to stop you in your tracks.

The British and Spanish are sailing the seas too, and don’t forget the Legendary ships and a brand new naval encounter that’s tougher than almost everything else. If you want to survive these intense late-game battles, you’ll need the best ship in the game — the ultimate ship.

Once you’ve upgraded your Harbormaster at Great Inagua to the max, you’ll notice that the final upgrade of almost every ship part requires Ultimate Plans. These plans can be found buried in treasure chests and within sunken wreckages around the world of AC: Black Flag Resynced, and in this guide, we’re breaking down where and how you can find every single one of them.

All Diving Bell Ultimate Plan locations – Black Flag Resynced

You’ll unlock the Diving Bell over the course of the main game, and it’s required for accessing several sunken wrecks across the seas. Most of the sunken wreckages actually contain an Ultimate Plan for one of your ship parts, so it’s worth fully exploring all of them. Ultimate Plans will always be found within a Secret chest and not a standard Chest.

Hull Armor Ultimate Plan location

The Hull Armor Ultimate Plan can be found in the San Ignacio Wreck in the Dry Tortuga Sea, Northeast of Havana. Dive down and look for a large chest within a half-shipwreck.

Mortars Ultimate Plan location

The Mortar Ultimate Plan shouldn’t be missed, and you can find it within the Antocha Wreck, Northwest of Great Inagua. Watch out for the shark in the area, and you’ll find this within a large chest in a shipwreck.

Ram Ultimate Plan location

This Ultimate Plan can be found within the La Concepción Wreck, Southeast of Fort Chinchorro in the Chinchorro Sea.

Swivel Guns Ultimate Plan location

Can be found within the Devil’s Eye Caverns, West of Cabo de Cruz Fort in the Cruz Sea. This might be the trickiest of the plans you need to dive for, as it’s within a long series of caverns. Once you’re able to emerge on “dry” land, you’ll know the plan is nearby.

Broadside Cannons Number Ultimate Plan location

Found within The Blue Hole, West of Kingston, in the Charlotte Sea. This chest isn’t surrounded by an obvious shipwreck, it’s just on the sea floor in a corner.

Round Shot Ultimate Plan location

The final Ultimate Plan you need to go diving for is in the Kabah Ruins, East of Kingston, in the Navassa Sea. This plan is at the end of a long cavern on the North side of the diving zone.

All Treasure Map Ultimate Plan locations – Black Flag Resynced

The other Ultimate Plans you need can be found by uncovering buried treasure. First, you need to locate the required Treasure Map, and then locate where the treasure is buried — it can only be done in that order, and Edward will remark when you’re near buried treasure. Below, we’re going to tell you which island you can find the relevant Treasure Map on, and where you can uncover the buried treasure containing the Ultimate Plans you need.

Mortar Storage Ultimate Plan location

• Treasure Map location: Tortuga

This buried treasure can be dug up on Matanzas, near a Mayan Stelae, behind a waterfall.

Heavy Shot Strength Ultimate Plan location

• Treasure Map location: Ambergris Key

This can be found on Misteriosa. If you already have the Viewpoint synchronised, you can find the buried treasure near a fountain just behind it.

Heavy Shot Storage Ultimate Plan location

• Treasure Map location: Cayman Sound

This plan can be found in San Juan. Once you locate the waterfall near the rear of the cave, walk behind it to find the buried treasure. Note, you should probably get the Treasure Map from Santanillas before visiting Petite Caverne, as the Fire Barrel Strength Ultimate Plan can be dug up here. Another Ultimate Plan you need will require the Treasure Map from this location, too.

Fire Barrel Strength Ultimate Plan location

• Treasure Map location: Santanillas

Once you make your way inside Petite Caverne, you can find the Fire Barrel Strength Ultimate Plan right near the entrance, where you find two guards. Take them out, and look to the left side of the upturned cart leading upwards to find the buried treasure.

Fire Barrel Storage Ultimate Plan location

• Treasure Map location: Petite Caverne

This Ultimate Plan can be found on Tulum. Look for shipwrecks on the beach to the South of the island, and head to the Southernmost point underneath a palm tree to reveal the buried treasure.

Harpoon Strength Ultimate Plan location

• Treasure Map location: Mariguana Island

It might be something you rarely ever use, but you’ll need it for tougher sea creatures. The Harpoon Strength Ultimate Plan can be found on Andreas Island, to the South. There’s a tiny patch of dry land with a single palm tree on it, and that’s where you’ll find the buried treasure.