The Moonchild's Ocean (A part of the Elemental Witches series)

There is murder around the beach when the evil sea wizard arrives from the sea, and the fisherman is found dead. An intelligent detective named Kyle Halloran was born with a Cancer zodiac sign and is a good wizard of the sea, his father died a hero and his mother is nowhere to be found, leaving him and his younger twin siblings to live on their own in a beach house with their maternal uncle, Daniel.

Kyle has the ability of Hydrokinesis and has sea magic in him, he also communicates with the sea creatures. He began to go with the mysterious, supernaturalistic cases to solve. He meets a mysterious, slightly older woman named Scarlett Moonstone, a beautiful astrologer of all and she joins forces with him on the case to stop the evil wizard of the seas. They meet the fisherman's nephew, Lance Abraham, and start a quest.