This has the potential to be a lot more.There is so much going on that sometimes less is more and it doesn't all have to be packed into one book.Kudos to the author for slipping in the ecological and environmental agenda and making it part and parcel of the fantastical scenario. This way it is calling attention to an almost hidden toxic problem, which is being ignored on a global level, whilst entertaining the reader with stories of merpeople.The various tribes of merpeople are quite vast and complex. A prologue or glossary might be a good idea.Personally I thought the Brent storyline lacked a concise explanation. Why wasn't he in a genetic and/or physical position to react the way his sister did?Overall I think this story could have stronger character development and do with more focus on the main plot instead of wandering off on ten different tangents. The typical YA feel is there, but suffers a little by being a bit drab and teenagey.Hardy needs to own her merpeople and that complex history she has created. Show the reader that creativity with a more determined stance, rather than letting us fill in the blanks.I received a free copy of this book via NetGalley.