Here is the full list of all 14 Submerged: Hidden Depths achievements. It takes around 6-8 hours to unlock all of the achievements on Windows.
Collect all Creatures
Collect all Boat Boosts
Visit all Landmarks
Collect all Styles
View a Relic at the Home Base
Change Body Style
Change Hair Style
Change Boat Style
Collect all Diaries
Finish the Campaign
Collect all Flowers
Collect all Relics
Use all Lookouts
Put a Flower in your hair