Hazel Bly and the Deep Blue Sea is a middle grade fiction written by Ashley Herring Blake and published on May 25, 2021, by Little, Brown.

The central theme of Hazel Bly and the Deep Blue Sea is grief, more specifically the loss of a parent at a young age.

"[4] Another starred review, this time by the School Library Journal, said the author's writing and extensive character development "allow readers to empathize with Hazel.

"[5] Shoshana Flax, writing for The Horn Book, commented on Blake's ability at balancing "many plot elements, often serious ones, without overburdening the narrative" which led to a novel that focuses on the development of its characters.

[3] A review by The Booklist called Hazel Bly and the Deep Blue Sea "a moving story of grief and guilt," and noted the book is composed of both very sad as well as very uplifting moments.