When I was younger, I loved mermaid books, movies, TV shows, etc. It's fun to see YA tackle this genre so I was really excited for DEEP BLUE. Although it wasn't exactly what I was hoping for, it was still enjoyable, but confusing. 
 From page one, we are thrown into this huge, complex world. There was obviously a lot of set up and planning that went into the world building, but it just drowns you. (pun intended) There are so many made up names and words and customs this one needs its own glossary. It was so overwhelming in the beginning I almost wanted to put it down in frustration. My brain hurt trying to pull all of this together and keep up. 
 DEEP BLUE is best geared toward a younger audience. It has almost a Middle Grade feel, and I think younger teens will probably appreciate it more. It's also fairly clean except for violence, there wasn't really any romance even though the synopsis hinted at it. The focus here is definitely the friendship and growing bond between the mermaids. 
 There is a cliffhanger. It's almost cruel, especially since the book was really picking up and the end was abrupt. That's not to say that the rest of the book had a slow pace because I never felt bored. This book definitely left me wondering about a few things and I will be on the lookout for a sequel because this one was just setting everything up.