Shade and the Castle by the Sea — Marilyn Peake

With all the other fish in the sea, your first crush needn't be human.

Shade and her best friend, Kai Zahnii, begin their freshman year at Ocean View College. Located on a secret island off the coast of California, Ocean View is a special place specifically designed to train students with magical abilities. Shade is a ghost whisperer. Kai is an empath and healer with the innate ability to become a Navajo shaman. On campus, their worldview is expanded as they meet witches, faeries, selkies, shapeshifters and others like themselves.

Ocean View has incredible facilities and buildings that look like castles. Down by the sea, merpeople interact with students. In the waters off a remote stretch of beach, Shade meets a merman with whom she falls deeply in love. Everything seems idyllic and magical. That is, until Shade discovers a horrible secret about the college, one that will haunt her dreams and waking moments.