Here is the full list of all 10 The Archipelago Promise achievements.
You discovered Caldera Island! It seems like you're not the only one here...
Reach the cave
You have found your brother and ended the game. Congratulations!
No, you can't swim in this game!
Sleep in the boat's cabin.
Find Dina's Lab.
You've set ashore on Mospeir Island!
Poor rabbits...
You've managed to kill the guard of Caldera Island!
More meat is exactly what I needed!