This could've been a 5-star read. The first 30% was great - tense and suspenseful, but the rest of the book (up until 70%) was too slow. Also, the plot gets a little repetitive after their first dive. The overall atmosphere was incredible. I was completely enamored with the story and the characters. I needed to know what was going to happen in the end and if everyone will be alright. Since this is a plot-heavy book, the characters were a little flat, but I didn't mind. The spooky parts were quite mild and I wish they happened earlier in the book, but I still enjoyed them. The whole mystery behind the sunken SS Arcadia was underwhelming. One of the characters gives a half explanation in one paragraph, and it is never mentioned again. I honestly thought the divers were going to find more clues about what caused the Arcadia crew to 'go insane', instead of that one specific thing, which is the only evidence for the aforementioned explanation. This book reminds me of the videogame from the Dark Pictures Anthology: Man of Medan. From Below and Man of Medan have a similarly structured plot and their mystery element is quite similar, but the contexts are completely different.