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.
For escaping the bulkheads
Got all achievements
For navigating the shark caves
Unlocked all three endings
For picking a really stupid alias
For sorting all the groceries
For getting kidnapped
For making it to the human world