Here is the full list of all 13 Fantasy Friends: Under The Sea achievements.
Complete the tutorial.
Interact with a decorative object in the plaza.
Use an involution potion.
Evolve your first pet.
A new creature is born!
Get a show of affection from your pet!
Get your first skin.
Find a treasure!
Cure a pet
Get all 12 pets!
Play All Unique Interactions.
Get all skins.
Unlock all achievements!