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.
Finish the Campaign
Collect all Flowers
Collect all Styles
Collect all Diaries
Collect all Creatures
Collect all Boat Boosts
Collect all Relics
Visit all Landmarks
Use all Lookouts
Change Hair Style
Change Body Style
Change Boat Style
View a Relic at the Home Base
Put a Flower in your hair