It's a very creepy tale, unfolding at first very quickly and then stretching out over weeks and months. Kerry is a fully formed protagonist given an impossible task, and its her human ties--her fear of the water and love for her daughter--that makes it so easy to relate to her.
I wasn't expecting the ending of this one, and it was delightful to be surprised like that. It took me a day to process it, as I had to decide whether I liked the story or not.
It's a horrible, terrible, unsettling final act, so it succeeds as top-shelf horror. Kudos to Brian Hodge on this one...