Here is the full list of all 31 Windward achievements. It takes around 40-50 hours to unlock all of the achievements on Windows.
Sink another player in PvP.
Defeat an enemy by yourself without taking any damage.
Find and equip your first epic item.
Complete two consignments at the same time.
Become a true pirate. Arrr!
Make a town grow in size.
Do your first trade run.
Complete 50 commissions.
Defeat a Pirate Captain.
Defeat two enemies back to back.
Achieve a skull kill rating.
Opt out of a PvP match by using a White Flag.
Hire a follower.
Upgrade your ship.
Defeat 5 pirates.
Customize your ship's look.
Open a Sealed Letter.
Complete your first commission.
Unlock all ships.
Defeat 100 ships.
Establish a foothold in a region where your faction has no towns.
Completely drive out pirates from a level 9+ region.
Equip an item that will push any stat above 1000.
Drop Grogolov on top of 3 or more enemies.
Successfully complete a commission to place a Guard Tower near a town.
Capture a level 9 or higher region in a co-op match.
Sink a pirate captain in a level 39+ region.
Drive out pirates from a level 39+ region.
Repair your ship while obscured by fog.
Achieve the Admiral reputation standing with any faction.
Complete the Strange Diagram quest.