Here is the full list of all 26 Braveland Pirate achievements. It takes around 15-20 hours to unlock all of the achievements on Windows.
Game completed using only the hard level of difficulty.
Rejected all the assassination contracts.
Rejected the Iron Bank's offer.
Have won 150 battles.
The Great Reaper defeated.
Game completed without using the easy level of difficulty.
All the bosses defeated.
Looted all treasure chests and hidden caches.
All pirate tricks learned.
Visited all islands.
Jarl Erik defeated.
Fulfilled all the assassination contracts.
Six pirate tricks learned.
Have answered all the questions of the sages.
Obtained the old man's artefact in the sea.
Have overcome 25 random encounters in the sea.
Sir Rodrick defeated.
Bought an item for hero.
Page on Facebook or Twitter visited.
Fought through all dungeons and arenas.
All four equipment items on.
Davy Jones defeated.
Looted 7 treasure chests and hidden caches.
Pirate trick learned.
You defeated the army without losing a single warrior.
Cabin boys have joined you.