Rating: 2/5 
 ***Minor spoilers*** 
 I've never read a book about mermaids before, and I went in not knowing what to expect. I picked up this book because I wanted to give them a try, and it turns out they aren't really my thing. It might just be this book, but I didn't really find them entertaining from my experience with this. 
 Deep Blue is mainly about a girl named Serafina who is heir to the kingdom or Miromara. She must go through something called a Dokimi which ensures that she is right for the throne, and ends with her betrothal to somebody she had no say in choosing, the crown prince of Matali. However, before she is betrothed, her Dokimi is attacked by assassins from Ondolina who kill her father and injure her mother. Serafina and her best friend, Neela, must run from Miromara and leave everyone behind, but for some reason, the assassins are after them. 
 This book was so confusing at the beginning. We're given a ton of names and places and stuff about politics that I had no idea what was going on. As well, there were also a ton of made up words and plays on words that it was a bit annoying. I found some of the words really childish and cheesy. For example, instead of saying "cool" they say "riptide" and instead of girlfriend or boyfriend they say "merlfriend." As I continued reading I became used to it, but I still found it pretty annoying. 
 The story on its own was pretty interesting, but I found the way it was delivered subpar, and it seemed as if the book was written for middle grade rather than young adult. I also didn't really feel any attachment to the characters. To be honest, I wouldn't have really cared that much if one of them died. 
 I also found the ending pretty ridiculous. I didn't really consider it a real ending. Nothing was really resolved and it wasn't even really a cliffhanger, but more of a "to be continued" if that makes sense. It didn't leave me anxious to discover what was going to happen next, it just left me annoyed that we didn't get a true ending. 
 Overall, I didn't think the premise was bad, but the writing itself could have been better. I found the book a bit childish even though I enjoy some middle grade books. I wouldn't really recommend it unless you're into books about mermaids. If you do try to read it, I hope you have better luck than I did.