Where the People Are
For making it to the human world


Poor Unfortunate Soul
For getting kidnapped

Wobbegong Winner
For navigating the shark caves

The puzzles are easy and you can just keep guessing until you get the right answer, but in case you're, like, super lazy:
Place five teeth
Hammerheads are stronger than Wobbegongs
Wobbegong
Hammerheads > Saw Shark + Wobbegong
Bull shark -> Hammerhead -> Sand shark -> Saw shark -> Wobbegong


Best Bagger
For sorting all the groceries

The letters should spell out "Ego sum syrena"


Titanic Tussle
For escaping the bulkheads

You can just call for help if you get stuck, but again, for lazy people:

Search all areas until you can't anymore.
Use the boot on the mashed potatoes.
Use the lettuce on the rabbit.
Use the key on the box.
Use the crowbar on the ice.
Use the scissors on the sock.
Use the spoon on the clam.
Use the pearl on the marble container.
Use the crystal on the sunbeam.
Use the hammer on the floor.
Push the crate against the wall.


Puzzle Pro
For solving all the puzzles.

You need to solve them all in the same playthrough.

How Do You Even Spell That?
For picking a really stupid alias

Give your mermaid the human alias of first name Argle and/or last name Fumph.


Completionist
Unlocked all three endings

None of the choices matter until the very end. Choose to destroy the Titanic (Ending 1), or choose not to destroy it, then either ask Maynard for help (Ending 2) or don't (Ending 3).

There are also two fake/bad endings (which don't matter for achievements) in the kidnapping scene if you try to seduce Maynard or attack with your tail twice.


Completionist
Got all achievements