Thank you to NetGalley and Orbit Books for this advanced copy! You can pick up A Letter to the Luminous Deep on April 23, 2024.

This was one of the most unique stories I've ever read. The underwater setting was fascinating and stunning, as was how the author split society into different Schools of Scholarship. The writing style also reflected this academic setting, in a similar vein to Emily Wilde (but with less fae and more underwater phenomena). I like how we saw the story emerge through both past and present letters, and I appreciated the intersection of so many different characters and relationships purely through the written word.

I do with this book was a bit of an easier read. The academic language and underwater jargon did slow me down when normally an epistolary-style book reads quickly. But if you're in the right mood/headspace to savor a book, this is the right story for you!

I have few words to describe this beyond <b>whimsical delight</b>. I had the absolute pleasure of reading this book on a beach longer by the sea, and can't imagine experiencing it any other way. I've never read an epistolary style novel cover to cover, mostly because I often find narratives told through letters to lack description and adequate characterization, but I can confidently say that Sylvie Cathrall has converted me. Her expertise stems in part from experience - I was delighted to read in the author's note that her current husband was her former penpal - but also from her old-world Victorian prose and breaktaking visuals of life on the ocean floor.

The story takes place in fabulously imaginative society of sea-faring academics made up of three different floating schools with competing approaches to academic inquiry. As a PhD student myself, I loved the references to academic politics and interdepartmental rivalries, but also appreciated how Cathrall interrogates the more toxic practices of cut-throat competition and workhorse mentality. The narrative itself is spun through a series of letters, press releases, and news periodicals, as two strangers, Sophy and Vyrein, try to piece together the mysterious disappearance of their siblings at an undersea architectural marvel known as The Deep House (which also happens to be Sophy's childhood home). However, the stars of the story are two people we never actually encounter in the present: Sophy's curious but reclusive sister E. and Vyrein's brilliant but anxious brother Henery, whose personalities and budding romance are revealed as their siblings work through their letters to each other and to other characters in order to understand what happened to them.

In addition to being a highly creative fantasy novel, Cathrall's debut is also one of the more excellent depictions of mental health in fiction I've encountered. E. struggles with severe OCD and Henery with disabling social anxiety, and Cathrall eloquently explores not only how these conditions impact their lives but also how they can be effectively treated, drawing connections to real-life efficacious therapies such as exposure and response prevention and cognitive restructuring.

Although the prose could be overly elaborate and the pacing slow at times, I couldn't help but care deeply about the characters and be drawn in to Cathrall's aquatic imagination.

*this review contains some spoilers*

Through reading letters and emails between characters, you learn about an interesting underwater world. I loved the deep relationships between characters. I especially appreciated the focus on the relationship between Sophy and E - I love centering strong relationships between sisters. I also thought it was interesting how E felt more comfortable sharing some aspects of her life experiences with Henery compared to Sophy - highlighted some of the complexities of our relationships and how we decide what to share with whom. I personally found the structure of the story a little bit confusing because you had to keep in mind both the author and the audience for each letter. It was helpful that they were clearly marked, but it did make it more difficult for me to get into the world building. However, if you like the style of it all being letters back and forth I think you will love this book! The book is pretty slow at the beginning and picks up about 80% through.

3.5/5. Thank you to Net Galley for providing a copy of this book in exchange for a review.

3.5/5 Stars.

As indicated by the gorgeous cover, the majority of this book takes place in the richly atmospheric world beneath the waves. This is an epistolary novel, with the mystery and plot slowly revealed by two sets of pen pals in both the past and the present.

The greatest strengths of this book are the intrigue and the immersion. My curiosity about the plot made me keep turning the pages. I also enjoyed the academic tone with which the letters were written, it felt like a refreshing change of pace from normal conversation. It was very fun imagining the reef outside the deep house, the terrifying endless black of the ridge expedition, and the floating cities that make up this world. The setting was very enchanting, but the world building was all very surface level. I found myself struggling to clearly visualize what the cities were supposed to look like, and confused about many aspects of their society. I wish that some things were more fleshed out and explained more clearly.

The place where this book really falls flat is the pacing. Not only were some parts very difficult to get through, but the ending felt very abrupt and unsatisfying. Perhaps this is due partly to the fact that it wasn’t clear that this is the first book of a series. This book also felt constrained by the fact that it was purely told through letters, and instead of just embracing some of the inevitable fragmentation of the story, the author forced some situations in a way that broke immersion for me. For example, there is a scene where two characters end up writing to one another because the noise from people talking downstairs at a party somehow drowns out their voices.

Overall, I still enjoyed this book. It was a unique concept, setting and format. I think that
I’m curious enough to find out what happens that I’ll continue the series when book two is released. This had so much potential that it did not quite live up to, but I think that the series can definitely be redeemed if the author fixes some of the common criticisms in the next book.

Thank you to the author, Orbit Books and NetGalley for a free ARC in exchange for an honest review.

I could not finish this book. I do not think I was the target audience for this. I will not post a star rating on goodreads because I don't want to sway the ratings due to my personal dislike. Sadly I do have to post one here for me to submit this. I think this could work for some people. It just didn't with me.

Thank you to NetGalley and Orbit for providing me with this ARC.

I really wanted to like A Letter to the Luminous Deep—the cover is lovely, the concept is unique, the characters are likable, and the epistolary style is immersive. This was one of my most anticipated books of the year, but unfortunately, it was very difficult for me to even reach 34% of the way through the novel, let alone push through the rest of it. And it’s not because A Letter to the Luminous Deep is poorly written or anything like that, it just moved incredibly slowly.

The story is told exclusively through letters and occasionally, through other pieces of writing, like diary entries and field journals. Readers learn that two characters, E. and Scholar Henerey Clel, who struggle to make friends due to their introverted and anxious natures, start a timid correspondence over a mysterious fish. We have access to their letters and are able to witness their mutual growing importance to each other due to their siblings, Sophy and Vyerin. The siblings are going through the correspondence of E. And Henerey in attempts to piece together what became of them, as the two disappeared from E.’s now destroyed underwater home without a trace.

I was incredibly intrigued by the mystery of their disappearance and by another puzzle A Letter to the Luminous Deep presents. Admittedly, I felt like I was following breadcrumbs of information through the woods—there were hints at the larger world, with remarks to a global, devastating event, known as The Dive, that rendered humanity forever changed. Tiny bits of information are only alluded to once every ten exchanged letters or so and the focus is truly on the humdrum of everyday life for these characters. It's even pretty easy to forget much of the novel is taking place underwater, when one is more frequently reading about things like the broken legs of a beloved chair and whatnot. It's not until about halfway through this 432 page book that the pace starts to pick up a little bit. I would have loved to learn more about the world of this novel, as a huge fan of BioShock, a videogame taking place in a dystopian, crumbling city built entirely under the sea, I am quite enamored with the concept of underwater life. I was excited to see what a different, healthier civilization under the waves would look like.

What little I gleaned about life in this water-based civilization was captivating. I did enjoy reading about the technology used—automaton porpoises to help researchers make it to the depths, portable habitats known as bubbles, research complexes under the sea known as the Spheres, and mail boats. Though all of these technologies were fascinating to me, they take a back seat to the daily life of E. and to that of other characters, and all descriptions of them are disappointingly vague. I felt I wasn't given enough details to even form a clear picture of what these technologies looked like. And I never learned how they were developed or how exactly they worked. I couldn't help but to be bummed to not know more of the nitty gritty details of this world and how it functioned and felt frustrated that the novel only scratched the surface of this information time and time again.

It was my persistent interest in these breadcrumbs involving the world and also those regarding the mystery of the characters which kept me pushing until I finished the novel. I considered DNF-ing multiple times because I was concerned that the hints weren't ever going anywhere, and nothing eventful was ever going to happen, but I prevailed. Unfortunately, my reward was a cliffhanger, but more on that later.

Though the prose of A Letter to the Luminous Deep is lovely and the letters shared create an intimate atmosphere, it was very difficult for me to focus on their content, which were written in the same tone and voice for all of the different characters, who were sometimes from quite different walks of life or of very different ages. All characters wrote in rather formal, somewhat antiquated colloquialisms, which consists of saying things along the lines of:

“Perhaps your mood has lifted even more since you responded to Scholar Clel’s letter, as I assume you have now? I can hardly count the number of times I have tried to convince you that occasional conversation with a kindred spirit can cure most ills.”

“Though I dare not say that I wish I were not a Scholar, I have felt of late a desire to escape to—to—well, somewhere else, and at present, I can think of no better elsewhere than the world you inhabit.”

This lack of variation between the letters and the writers made it difficult to discern who was writing to whom and the labels before each letter became indispensable to making this distinction. At one point, the novel offhandedly tells us that this is the speech everyone in the academic world uses, but I can't fathom there being no other distinguishing features between the written word of such different characters, some of whom aren't even scholars. There are no catch phrases, grammar quirks, technical jargon from different careers, or anything else distinguishing them from each other. Different fonts would have at least helped differentiate the writers, but there aren't any used. The biggest difference we see in the letters is that one character doesn't like to use the automated post system, which I gathered is something vaguely resembling underwater email.

Despite the notable lack of difference in the characters' written word, something that seems quite pivotal in an epistolary novel, I did come to care for main character E.. I struggled to feel invested in other characters, as they just weren't as compelling or sympathetic to me. E.'s younger sister, Sophy, is much more outgoing and details her own queer, slow-burn romance through her letters to her sister. This romance worked a bit better for me than the deepening bond between Henerey and E.—I think because it felt like Sophy and her love interest were on more equal footing. E., who is for all intents and purposes a shut-in due to her mental health struggles, has plenty to offer as a pen pal, but I worried for her ability to be a partner for someone actively taking part in the world.

On top of making E. such a sympathetic character,  A Letter to the Luminous Deep makes life under the ocean or Sophy’s free deep dives as part of a research team feel cozy and unthreatening. It makes the ocean feel like a wondrous place just waiting to be discovered rather than a dark, deep unfathomable abyss filled with monstrous looking creatures. However unlike other cozy fantasies, like Bookshops & Bonedust, I felt that there just wasn't a whole of substance and that not much was actually happening. At the point of the novel that I almost stopped reading for good, the biggest thing that had happened was that E.’s brother and his fiancée had come to live with her and she found the sudden invasion and forced cohabitation deeply unpleasant. Meanwhile, Sophy and Vyerin, commented to each other on the correspondence of E. and Henerey and took note of the deepening bond between their two kindred spirit siblings, something that readers have already noticed for themselves.

Unfortunately, every time I picked up A Letter to the Luminous Deep, it felt like a losing battle against myself, as my consciousness slipped away.  It was a struggle to reign myself in enough to focus on the novel. Though I kept hoping that the mysteries or more information on the world would take center stage, they didn't until almost the very end of the novel. To make matters worse, A Letter to the Luminous Deep then ends on a cliffhanger, leaving readers practically none the wiser about what E. and Henerey’s disappearance means for humanity. I am not 100 percent certain if I will read the next novel in the series, as I'm not sure I want to deal with the wretchedly slow pace again, but my interest in the world-building and the pervasive mystery is probably enough for me to give the series one more try.

Oh man this book was fascinating. It's written entirely in letters - dialogue is rare (and recapped in the letters) - which was intimidating but once I adjusted, I thought it was well executed, though a little dull at times.

The setting is so cool. I LOVED the Deep House and the worldbuilding in general. I thought it was really interesting and unique! But I would have preferred some non-letter interaction with the world. I loved that there were some illustrations in this.

This novel is very dense and slow. While there are moments of intrigue, a lot of this book was comprised of nothing important happening. This won't be for everyone... but I enjoyed it! I will pick up the next one once it releases because the ending definitely has me interested.

Thank you NetGalley for the advanced reader copy!

This was such a beautiful book and the writing was enjoyable to read!

E. Cidnosin resides in the Deep House and Henerey Clel, developing an epistolary relationship. Then, something happens that I find to be distasteful: multiple POVs and too many story perspectives/characters.

The story becomes hard to get into and the timeline becomes convoluted. I am sad to admit this, because the cover is so beautiful. The book itself was so exciting, the way it was advertised.

I was counting down the days. It was not all bad. The beggining made it difficult to keep coming back to it.

The intimacy of the story is striking. It reads like a half-remembered love story. It's charming, whimsical, without much depth. That in itself is not terrible, I do require a light mysterious read every once in a while to give my brain a break.

I like the idea of the sea being a permanent home, where everyone lives and thrives. The world sounds beautiful and exciting with the beasts. Abyss adventures.

The love story is a slow burn. Great representation. Mental illness is sprinkled in. Dive into this fantastical marine world! 🌟🌟🌟/5 Stars!

I’d read so many raving reviews of this book and how cozy and romantic it is but unfortunately it just wasn’t for me. The writing was a far too descriptive on the day to day and too formal to really get into. I also wasn’t a fan of the letter format.

Going based off the cover, which is so incredibly beautiful, and the description I really thought I’d like this book. However, the writing style felt a bit messy. The narrative style was interesting but unfortunately didn’t work for me personally. I found it to be confusing and though there were four different characters, they were all written the same exact way so it never felt like four separate characters.

The idea was there, I just didn’t like how this story was executed.

This will be a solid fantasy for some but unfortunately it was not for me. I’m not a huge fan of books that are this “cozy” and slow moving. I think if you enjoyed the Emily Wilde series then you should definitely give this a try!

Thank you Orbit Books, Net Galley, and of course, Sylvie Cathrall for an advanced reader copy (ARC) in exchange for my honest review.

This is a great read for fans of Emily Wilde’s Encyclopedia of Faeries, Fathomfolk, and Voyage of the Damned.

First off WHAT a unique read! I felt like I was solving a mystery reading all the correspondence between various characters. Yes, I of course had many questions at first and had to re-read a few passages, but it was honestly fun! The writing flowed so meticulously and was poetic. Additionally, the world building, queer characters, and the character depth was IMPECCABLE to say the least! I’ve never read a book completely in epistolary format! Truly a unique experience and it made more sense (and was also very cute) upon learning that the author married her pen pal!

I felt a kindred connection with the protagonist’s version of OCD in the novel - I too have lived most of life affected by certain rules ruminations/compulsions I have to follow. OCD is a spectrum and can vary from person to person, however, to read about a protagonist written so beautifully without any of the cliches or myths that society views OCD as was so refreshing. Not to say this novel is the first of its kind, but I loved that aspect.

Going back to the world building, there is a LOT OF INFORMATION and characters to keep track of (I’m not complaining). Because of this, I’m excited that this book is NOT a standalone. I’m excited for next books in this series!

TLDR: I recommend this book! Sylvie Cathrall’s debut novel was SO SO GREAT. Yes, you may have questions, but that’s what makes this story beautiful! I want to know what goes on in this author’s mind!

I have a hard time raring this one. It's an intriguing story. However I've come to realize the journal, letter, etc story format just isn't for me.

Writing letters is, in this day and age, a lost art. Kids no longer pass notes across desks when the teacher isn’t looking; they send quick texts from phones held discreetly in their laps. Postcards and notes to relatives pepper more museum displays than fridge doors and bulletin boards. The simple act of putting pen to paper itself is becoming increasingly uncommon, and yet, the romantic appeal of receiving an envelope in the mail with our loved one’s name and address scrawled in the top left corner has yet to leave our collective consciousness.

Enter Sylvie Cathrall’s debut novel. Steeped with rich language and a spellbinding setting beneath the waves of the sea, A Letter to the Luminous Deep is told entirely in letters sent back and forth between characters, making the book read more like a long lost journal than a modern novel you can pull off the shelf of your nearest bookstore.

After noticing some odd activity outside the windows of The Deep House, an architectural marvel built among coral beds and glimmering sea life, E reaches out to Scholar Henerey Clel to report her findings. To her surprise, Henerey writes her back, and the two begin a correspondence to discuss E’s home, surroundings, and later, their personal lives.

Less than a year after trading letters, E and Henerey disappear, with the legendary Deep House falling into ruin after a seaquake.

Mourning the disappearances- and assumed deaths- of their siblings, E’s sister Sophy and Henerey’s brother Vyerin begin trading letters of their own, quickly establishing a mutual goal of uncovering what happened to their beloved siblings. Sophy and Vyerin decide to read and share the letters written by E and Henerey to see if any clues reside there.

As Sophy and Vyerin share more of their personal lives, their research expands to other journals, writings, and mail recorded by and sent to E and Henerey. What they discover radicalizes their view of the world itself.

With beautiful characters, a unique underwater setting, and no shortage of scientific intrigue, A Letter to the Luminous Deep has earned its place among other contemporary science fiction and fantasy authors, including the likes of Heather Fawcett (Emily Wilde’s Encyclopedia of Faeries) and Rebecca Ross (Divine Rivals).

Pushed myself to get to 20% but wanted to DNF as soon as 7-8% 😭I LOVE epistolary books, but the setup and beginning didn't work for me. The letters honestly didn't really give me many vibes to work with either, imo. Every single character wrote in the same voice and I constantly had to reread the headers to make sure I knew who was talking to who.

Since I kept getting taken out of the story, I really did not feel invested in what was being discussed nor did I feel connected to any of the characters so far to want to continue reading long letters about their lives. Maybe the author did break things up more by adding more articles/interviews in between, but I'm not sticking around to find out. 😂

ARC COPy...It was an interesting read (via the letter style approach) and I see why the narrative is categorized as "cozy", and felt like a slight "steampunky" travelogue cause of the vivid imagery description of the underwater world being described.

I want to thank netagalley for giving me an arc in exchange for my honest review.

I honestly did not like this book, I don’t think the story being told through letters help me understand the story at all. I wa honestly very confused and that took away my motivation to enjoy and keep reading it.

If you enjoy that style I think you’ll enjoy this book but it wasn’t for me

2.5 stars

I really wanted to love A Letter to the Luminous Deep, however I found the writing style to be difficult to get into. I love the epistolary format, but I found some of the letters to be too long winded or extremely academic which distracted me from the story.

"A Letter To The Luminous Deep" offers a fresh twist on the cozy mystery genre, unfolding entirely through letters.

Initially disorienting, the format gradually reveals a captivating web of intrigue and emotion as two unlikely individuals find love, only to disappear without a trace.

Despite its unconventional approach, the novel delivers a compelling tale of relationships and mystery, keeping readers engaged until the very end. Fans of cozy mysteries will find much to enjoy in this unique and heartwarming story.