Equestria and Earth had maintained peaceful negotiations for a while and now they formed an alliance, with ponies and humans crossing over to live and work in the other world.  

A Hippocampus filly was separated from her parents after a monster attack when playing in open waters, she was found and rescued by a human ex-navy biologist who decided to take care of her while the guards searched for them.

Now under the protection of her new human guardian, the filly must learn to live out of the water in a brand new world.

Author's Note:
Cover art by NebulaNovia.
This is a PoE/HiE fic.
Alternate Universe tag due to its different interpretation of Sea Ponies, who never were Hippogriffs.
Some tags will be added as the story progresses.