Here is the full list of all 18 Choice of the Pirate achievements.
Become the Pirate King.
Defeat the Lusca.
Steal from the Pirate King! You've got guts, Captain.
Rescue a mermaid.
Defeat the ghost ship.
Earn the notice of El Sabio.
Capture your first target without sinking it.
Convince Evan Lark to open up to you.
Acquire three ships to launch your fleet.
Acquire two ships to launch your fleet.
Acquire one ship to launch your fleet.
Remove the threat of Blackguard from your future.
Save Jim the Cabin Boy from an untimely death.
Turn over your first bounty to the Crown.
Become a spy for the Crown.
Fall under the curse of the ghost ship. Congratulations on your zombification!
Steer the Crown in the wrong direction.
Will those mutineers get what's coming to them?