If you love academia, this is for you. It's definitely on the cozy side of the fantasy world as well, which I enjoyed. I think that readers may have difficulty keeping up with the changing POVs throughout the story, but this storyline and writing style were both really interesting and has me intrigued to continue the series.

Good storyline lost some of the experience in keeping up with the letter format. Interesting concept just not my favorite format. I do believe most people will love it.

This epistolary novel is perfect for fantasy readers who enjoy an immersive underwater world with lush descriptions. Likeable, unique characters who develop a relationship through their exchange of letters and their shared quest to solve a mystery. For me, this was a slow burn book that I was able to casually pick up and then set aside as needed while reading a few other books simultaneously. This is not a negative statement, just a description of the pacing. However, despite the lack of a high action or fast-paced plot, I was still heavily invested in the characters and plot line. I would have preferred to have some character interaction outside of their exchanged letters, but the author still did a fantastic job at building intimacy via the letters. This is the start of a series, and I think it is a unique and lovely opening.

I'm a bit apprehensive to call anything cozy these days. Mostly due to the overall misconception between boring and soul-touching. I've been burned before. Now, I can say I got yet another novel that was touching and brought all those nice feelings. Despite being about lost siblings, this epistolary novel brings people together in a most interesting way - through letters and short messages. If there is one thing a millennial can relate to, that would be that. From a letter to an email to any messaging client software. The setting here is also interesting due to being underwater with a deep-sea exploration element. The book has something special about itself and I didn't expect to even go back and re-read the second half of it, since I felt like I brushed over the main plot. The story touches upon the unknown and how it can bring wonder and, at the same time appreciate what one currently has. I liked that.

I wanted very much to like this -- the description is so interesting and I love a good underwater fantasy. The idea that 2 pen pals exist in different world - one on land and on in the water seemed right up my alley. But alas I was let down, the prose and pacign jsut didn't do it for me. I just didn't care about the characters much - it felt like a book that was handed to me in 10th grade and told to read and thus - I reluctantly did. By the end I was just tired and disappointed.

I'm sorry I can't say anything more positive. Thanks to NetGalley and Orbit Books for the ARC.

This was such a magical story. I loved how it was told strictly through the form of letters and journal entries, but there was a variety of interactions from the past between our main characters, E. and Henerey. We also get the story of their siblings, Sophy and Vyerin, which is in the present tense and evolves as you go through the book.

A year ago, E. and Henerey mysteriously disappeared. Now, Sophy and Vyerin are trying to piece together what happened in the events leading up their disappearance by reading through their written communications with one another, their field logs, sketches of underwater creatures that were observed, and so much more!

I loved seeing the scientific method in action! E. sees something unusual, hypothesizes, and reaches out to Scholar Henerey to figure out what is happening outside of her window in her underwater home. What starts out as a request for knowledge leads into a beautiful friendship, first through communication and then in person as well!

There is also a very interesting story of what Sophy has discovered on her research mission, which she shares in her communications with Vyerin. There is so much scientific discovery happening throughout this story!

I will say that the pace is a little on the slower side, but it makes for a great comfy read if you have an interest in science, the underwater world, or magical fantasy. I was not expecting the cliffhanger (I initially didn’t realize that this was the first in a series) and will be eagerly awaiting the release of The Sunken Archives #2!

Thank you to the publisher and NetGalley for the eARC in exchange for an honest review!

alone in her underwater home following the departure of her siblings and the death of her mother, e. pens a letter to scholar henerey clel. their academic correspondence soon blossoms into more as they discover a mystery involving e.’s beloved family home and its architect, her late mother—until both vanish in a seaquake that destroys e.’s home. a year later, e.’s sister, sophy, and henerey’s brother, vyerin, attempt to solve the mystery of their siblings’ disappearance using the writings they left behind.

a letter to the luminous deep is an ambitious debut novel: a mystery within a mystery told through four perspectives and dual timelines in a fantastical underwater world. while i don’t expect a fast-paced adventure from an epistolary novel, so many of the letters dragged on and on and the characters’ voices were not unique enough to justify it. cathrall offers one of the better depictions of anxiety/social anxiety that i’ve come across in fantasy, but outside of that, the four main characters’ voices are almost indistinguishable (particularly in the first half of the novel). the last 100 or so pages were the best by far; i enjoyed seeing the pieces of the puzzle come together, and the ending left me curious about what will happen in the sequel.

A Letter to the Luminous Deep was an enjoyable cozy fantasy for me. I typically don’t enjoy reading books where the majority of the plot is told through letters. However, I thought that Cathrall expertly wove the character’s letters together in such a heartfelt way that I have a hard time imagining it written in any other style. It added to the mystery and Victorian feel of the plot, which intrigued me enough to keep going. There was something special about watching E. and Henerey fall in love through their correspondence — especially since they both struggled to socialize in face-to-face settings.

While I do love a good cozy fantasy, I did think the pacing was very slow. I wish this was one book, instead of what I’m assuming will be two with the cliffhanger ending in this one. In that respect, I felt a little cheated that I made it through the slow build up to an ending that didn’t quite deliver (at least not yet). I also felt that some of the surrounding characters’ back stories and motivations didn’t quite add up to me (Arvist, Seliara, their exiled Father, Chancellor Orelith, Jeime and Tevin). Arvist is a big problem, considering he basically closed out the novel with his account.

I would be interested in the second book, but likely wouldn’t run to read it despite a fairly enjoyable time with the first.

I thought this was really cute! I loved the epistilary format. Would be great for fans of an Encyclopedia of Faeries!

I received an arc for this book and I really wanted to love it because the cover was so beautiful but I just could not get into it. I tired several times to finish it but it was just not for me. It might be because I am now dipping my toes into fantasy but yeah, it wasnt for me.

It begins with a letter to Scholar Henerey Clel from E. Cidnosin and continues with more correspondence between siblings of the aforementioned characters, Sophy and Vyerin, who begin a "project" of compiled letters and other documents involving Henerey and E., themselves, and associates during the timeline of their evolving friendship, in an attempt to memorialize their lost siblings and understand what might have happened. Through numerous missives, deeper and more intimate relationships develop amongst the characters, and more details emerge, hoping to shed light on the mystery of their disappearance.

This was a very unique story told through documented letters, transcripts, and correspondence between multiple characters. It is written in a very scholarly manner with an air of constant learning and mystery. At times, I found myself skimming through the correspondence as it seemed so trivial and unimportant, but I understand the story is supposed to mirror personal correspondence letters. It was left on a cliffhanger, so the story is incomplete and leaves one feeling the loss of closure. It was frustrating, to say the least. Overall, it was an interesting read.

This was an interesting book with letters written back and forth. I would have liked more action in the present storyline. The book took a while to get into but was more exciting at the end. I look forward to the next book.

I was hoping for this to be a good deal like "Emily Wilde's Encyclopaedia of Faeries", which I really liked, and in some ways it was similar, but this was just far too slow, ponderous, and lacking in humor to really hold my attention or garner my love and undying affection.

This moved at a positively glacial pace. We explore letters between several sets of characters, whose personalities unfortunately come off as incredibly similar or incredibly dull, sometimes both. They all seem like lovely people, but also come off as very flat. Most of them struggle with neurodivergence of some sort or another and/or anxiety and social disorders, but I just struggled connecting and caring about them overall, and not because of the aforementioned. I've read plenty of books with similar characters, it just wasn't working for me here. I liked the friendship between Sophy and Vyerin, but E. and Henerey's romance just needed to be a little stronger to really have me rooting for them.

I think this definitely could have used some strong editing skills, and I do wish the characters had been stronger and felt more alive. I felt very removed from all the events happening, possibly due to the epistolary nature of the storytelling. I understand why that choice was made for the story, but I wonder if it may not have worked better to have one set of letters as a more formal traditional story with letters peppered throughout from some of the other characters. I dunno. Maybe that wouldn't have improved it any, but I think it may have made connection to the characters easier for me personally. At the end of the day, it's a perfectly fine book, but I can't see myself recommending it or seeking out the sequel(s).

My first thoughts on this book is that the cover is beautiful, I can only imagine the special editions that could be made! I wasn't sure how I would like the story being told in letter format, but it made the book easy to read for sure. It has tropes that I always like such as academia, underwater world, and mental health representation. I had a great time reading, thank you for the opportunity NetGalley and Orbit books!

Sophy and Vyerin have both lost their siblings, who are currently perfumed dead from an accident. Lost and confused, Sophy and Vyerin start up a correspondence to try to understand their siblings' lives, work, and relationship before their disappearances to assuage some of their grief. While their friendship develops they also begin to uncover the truth of their siblings' disappearances!

I was pleasantly surprised by this epistolary novel. With the number of characters and threads to follow with so many characters and just two corresponders, it could have gotten confusing. But instead it was easy to follow and easy to get invested in both of the parallel storyline. The world is super fascinating and the extremely academic and scholarly structure of the world is weird, but weirdly relatable to anyone who's been in academia. It was a cool backdrop for the lives of the characters and their personalities.

The mystery of the disappearance and the structure was engaging and the reveal was definitely interesting. The story does end on a bit of a cliffhanger and I'm curious to see how the story and it's structure change, if at all, in the next part. Recommend!

Thank you to Netgalley, the author and the publisher for an advanced copy!

I couldn’t finish this one, sorry! Everyone sounded the same and there was no coherent plot. The prose was too aggressively ornate and whimsical for me.

I’ll start with the fact that I seriously struggled with this book. I listened to the audiobook first. It didn’t work for me. The characters felt overly melodramatic for precious little reason. The story is almost completely in epistolary format.

There are two major set of letter writers that include Sophy and Vyerin in the current time and Sophy’s sister referred to as E. and Vyerin’s brother, Henerey, who started correspondence with each other about a year before their disappearance. Sophy and Vyerin share their siblings’ letters and other information including scientific articles to find out what happened to the couple.

After the audiobook failed me, I decided to read the book at a slower pace. I found I appreciated the prose and world slightly more when I only processed small pieces at a time. Each chapter contains several letters between various parties skipping back and forth through time from before the disappearance to after and exploring the relationships along with small tidbits about their world.

The letters are very formal and filled with all the general niceties observed in formal letter writing, checking on the wellness of the recipient and the mundane while lightly touching on the more pertinent subjects.

The characters in the story were filled with several scientific minds, but as soon as they started to detail their research, they would stop and indicate that the reader was obviously not interested in those details. So frustrating. I wanted more rays, nautilus and sea creatures and details about their habitats and migration patterns. But alas, I suppose that would distract from the character and relationship building, which was the larger focus in this story.

I’d give a limited recommendation for this book for those that love the formal prose of letter writing. The world in this fantasy is like a large blank canvas with only a few partial sketches filling in sections, but the relationships built between the characters are gradually revealed as the layers are slowly pulled back through each letter. And please note, this is book 1 so it ends with more questions than answers.

Thank you to Netgalley and Orbit Books for a copy provided for an honest review.

Audiobook - 2 stars
ebook - 3 stars

A Letter to the Luminous Deep of course drew me in with that absolutely stunning cover and the epistolary narrative. I was excited to get started with this one because it promised to stand out from my other books that month.

I did struggled a bit with the first about 40% of the book. While I really enjoyed the style of the narration and didn’t mind the pretty slow pace and constantly mixing timelines at all (I heard that this was confusing to some but it wasn’t bad to keep up with for me personally), I did have a really hard time with the formal language that was used between most of the characters. I always had to put the book down after a chapter or two and wouldn’t pick it up again until the next day.

Thankfully, after that first chunk of the book, when something really cute happened, I finally became completely invested in everything and the pages started to turn much more quickly for me. I had set a daily reading goal for the book for the rest of the month so I could use it for my last readathon prompt (had to finish it in May for it to count) but that was right when I became more invested in it and I blew those reading goals out of the water, reading double or even more every day and never wanting to put it down anymore. I was a little worried in the beginning since I had such high hopes for this book so I’m glad I grew to enjoy it so much eventually. It suddenly felt perfect for my reading mood. Maybe I also just needed to finish some of my other books as well before being able to fully focus on this one.

It turned into a really cute slow burn love story with representation of anxiety that I felt was very relatable and was integrated well into the story. I also loved how accepted it was by everyone around the character with anxiety rather than her being made to feel bad about it.

I did wish that there would’ve been more world building, especially about the history of the world, but that would’ve been difficult to integrate smoothly into the narrative style so I understand why there wasn’t more. Maybe there’ll be a way to get more of that in the next one.

It took some time for me to grow attached to some of the side characters but I really liked all of the main characters. They felt well developed to me and I enjoyed their various interactions (aside from the formal speech). It was also fun to see how the story brought all the characters together at the end. I’m looking forward to seeing how this will continue. It’s definitely more fantastical than I first expected.

Thank you to the publisher and NetGalley for an ARC in exchange for an honest review.

Let me start by saying that epistolary novels are not my particular favorite type of novel. I feel that they are ridiculous in many ways because I doubt that anyone would include THAT much flowery language to describe something so mundane as their daily interactions with other people. Especially when you think of exactly how long it would take to compose a letter of that length. A counterargument to that would be that during the Regency/Empire era in England it would be realistic. As a result, almost all epistolary books use the language of that particular time period regardless of when or where the story is designated to take place. As is the case with this book.

Due to the language use, a lot of the societal formalities of that time come into play and make the book come across conceptually as a comedy of manners. Which it most definitely is not. However, the ridiculous amount of "dithering" between E. and Henerey comes across a bit...cringe. It would make sense if these vignettes were taking place in person, but they are not. I find it hard to believe that in a place where paper is scarce (mentioned more than once in the text) they would spend so much paper to correct themselves or write asides or go on about how sorry they are that they did not reply sooner.

All of that ridiculousness aside, the book is not bad. I feel as though E. is a very relatable character, especially for those of us with social anxiety. I also approve of how supportive and healthy the relationship she has with Henerey is depicted. I think Sophy is written very well as a sister who is compassionate but still struggles to understand her older sister. The villain in the book is truly more of an ominous background presence for most of the story which is beneficial because it allows Cathrall to fully develop her world and the way that it functions. And it is a very interesting world to say the least. I know that the book is setting up the next in a series, so much of the story is not brought to a conclusive and definitive ending. I find that a bit frustrating because we discover so much at the end of the book. It feels like a cheat in some ways.



A drawback is that in a novel where we have multiple characters writing letters to describe the action, none of them have a truly unique voice. In fact, if each letter did not explain who it was from, I would not be able to determine it most of the time.

I am absolutely in love with this gorgeous book! I did not know it was told entirely in letters going in but I really enjoyed the format and felt like it fit the book so perfectly. I already have this staffed picked at the bookstore I work at and I cannot wait for the sequel! 4.5 rounded up