Here is the full list of all 22 The Sea Between achievements.
The first step to a long journey.
Retrieve the healing flower from the Rawls Forest.
Team up with Kira the Courageous.
Team up with Merritt.
Solve the mystery of Artoria's monster problem.
Help to stop the attack on Polaire.
Team up with Sir Adelyse.
Helped all people during the attack on Polaire.
Get Grace to safety in Vawn.
Gain access to the boat.
Reactivate Majoha's Light at the top of the tower.
Defeat the Dragon that lives in the Kalila Mountains
Learned the truth about the Empire's plans.
Find a locket that Adelyse keeps as a reminder of what she's lost.
Have Merritt gain the confidence to use the Dawnbringer spear.
Find the developer's secret house.
Prepare for the Empire's arrival.
Check 1 bookcase.
Check 25 bookcases.
Check 50 bookcases.
Check 75 bookcases.
Check 100 bookcases.