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