Assassin’s Creed 4 Black Flag Resynced Mortars Ultimate Plan Location

Mortars Ultimate Plan in Assassin’s Creed IV Black Flag Resynced is needed to buy the final Mortars ship upgrade at the harbourmaster.

Mortars Ultimate Upgrade Plan Location

Mortars Ultimate Plan is looted from an underwater chest in Antocha Shipwreck (600, 636).

For all other Plans refer to All Ultimate Upgrade Plan Locations and for everything else also check the Collectible Guide.