Although not expressly stated, this a sequel to Lockwood's previous book Below. Even though this is a stand alone book, the characters from Below are once again the protagonists, so reading that first will give you a greater understanding of their thoughts and explain some of their actions a little better.
I picked this up since I really enjoyed Below, and I'm always up for any kind of novel involving deep sea attacks by unknown creatures. Unfortunately this didn't work as well as its predecessor. The writing may have improved, but the flow of the story just wasn't as smooth as I would like. As with Below, there are also several chapters done from the POV of the creature, which after a while get a little repetitive. I get it, I mean what else do these things think about besides food? Probably not much so it's hard to see how else it could be done, but after the first two of these POV sections, I found myself skipping pages because the same thing happens - it senses some kind of vibration in the water, thinks it's either prey (lost count of how many times that word was used) or a threat and goes off to find it. Below also suffered from this, and maybe if I hadn't read them back to back it wouldn't bother me so much, but I don't think these kinds of books need the creature's POV because there's no need to justify their actions. This adds unnecessary filler. In any case, this was still a fun read