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