Excellent, unputdownable, creepy atmospheric stupendous story. Genuinely scary. For a more succinct and excellent review read this

https://www.goodreads.com/review/show/142777791?book_show_action=true&page=1

Hooked me in right from the start and had to finish reading it in one sitting. Now want to read it again ..... and the sequel. Just remember, keep the windows and doors closed and make sure the tide is in.