Here is the full list of all 9 Mermaid Mission: Titanic achievements. It takes around 0-1 hour to unlock all of the achievements on Windows.
For solving all the puzzles.
Unlocked all three endings
Got all achievements
For escaping the bulkheads
For picking a really stupid alias
For getting kidnapped
For sorting all the groceries
For making it to the human world
For navigating the shark caves