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.
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.
Looted all treasure chests and hidden caches.
Fulfilled all the assassination contracts.
All pirate tricks learned.
Jarl Erik defeated.
Have overcome 25 random encounters in the sea.
Fought through all dungeons and arenas.
Sir Rodrick defeated.
Six pirate tricks learned.
All four equipment items on.
Bought an item for hero.
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.
Page on Facebook or Twitter visited.
Have won 150 battles.
Rejected all the assassination contracts.
Have answered all the questions of the sages.
Obtained the old man's artefact in the sea.
Rejected the Iron Bank's offer.