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