The cover for this book is absolutely beautiful and when I read the synopsis I was intrigued on how this book would go. It took me a while to get into the style this book is written in, which is epistolary since the book is in the form of written and corresponding letters. It did have me confused for about half of the book since I did feel like a lot of characters and their different feelings/thoughts were shoved at me at once but towards the end I felt like I was able to understand it a bit better. I did kind of enjoy the character's, I feel like so far Sophy's sister E is my favorite and I'm hoping in the next book we can learn more about what happened. The story was also decently paced, and I don't have any complaints about how the story progressed nor the world building. I do think the world building is actually quite interesting, I mean I'd love to live underwater and I think the concept is cool.
Thank you to Netgalley and Orbit Books for an e-arc in exchange for an honest review

“CRUMPLED DRAFT OF LETTER WRITTEN BY HENEREY CLEL, 1002 
My dear E., 
I have thought of nothing else but you and your letter over the past day or so, and I do not intend to start thinking of anything else anytime soon” (pg 257, as well as the back cover)

This novel is an absolute enchantment. It weaves together the genres of Science Fiction, Romance, and Mystery with Victorian overtones in a way that will leave you longing for a time when people narrated their lives through beautifully written letters, or “Automative Post Missives” as they are called in this story. I had the pleasure of both reading and listening to this novel, and I must say, the Audible Book is one of the best multinarrator recitations I’ve ever experienced.
What is the plot? Well, Sophy  (a deep sea scientist/explorer) has lost her sister…her sister E has inexplicitly disappeared. E was a recluse of sorts, finding contentment in her underwater home, that is, until something curious occurs, so curious in fact that she seeks answers. The only way a recluse like E can find answers is to write to someone who may be an expert in such curiosities, Henerey. Charmingly enough, E and Henerey fall in love through their correspondence. When both E and Henerey vanish suddenly, Sophy and Henery’s brother Vyerin begin to work together (through letters, of course) to solve the mystery of their missing siblings. 
The novel comprises not only the letters of E, Henerey, Sophy and Vyerin but also a smattering of letters of other quirky yet charming characters. 
Not only is the plot of this novel intricate and mesmerising but so is the writing. This novel would make the most amazing mentor text for a junior and senior high classroom for a number of reasons: it would teach descriptive writing and how it creates mood and atmosphere as well as characterisation (through tone and word use). 
Teaching figurative language (some letters are incredibly poetic) as well as vocabulary.
Teaching narrative storytelling as well as letter writing ( a lost art, I am sure)
I mean, just read this passage: 
“ I should mention that the water felt different from the lovely sea to which I am accustomed. It seemed to ooze around me- warm and slippery, as though it had thickened like a custard. The sensory unpleasantness of the water, however, could not dim its visual splendour. Despite the imposing darkness, the water possessed a kind of luminescence: an odd purple and green and grey glimmer like the last moments of a sunset” (pg. 239).

This novel has the potential to inspire readers to write more beautifully. The descriptive passages, such as the ones I've shared, can serve as excellent examples for aspiring writers to emulate. I long to write this beautifully!

A beautiful book. I loved it. AND it sets itself up for a sequel!!!! Yay!!

I found the way in which this was written to be almost a slow burn. The more I read, the more I wanted to continue, but I did find it easy to put down in the beginning. Perhaps that was the intention, though. This feels like a novel that's not meant to be devoured in one go. There's a reflective quality about it. Something fascinating is how the book manages to pull off such interweaving plot threads. You have the story of two acquaintances reading the letters of their siblings (sister of one, brother of the other), two will-be more-than-friends who are in turn discussing their own scholarly research with each other...which of course sets off a chain of consequences for both of them. Then, going back to the original pair, you have them conversing with each other about their siblings' actions and the effect they've had. To say nothing of the spattering of tertiary sources (news articles, interviews, etc.) found throughout. It should be convoluted and hard to follow. Yet it's not. It's incredibly smooth. And what's more, the characters themselves come to life the more you read. You get a sense of who they are and who they portray themselves as.

The writing itself did feel a bit stilted at times. Yes, they're mainly writing letters to each other, and there's a sense of an intentionally old-fashioned style to them. However, it wasn't really until near a quarter of the book (or even a bit further) that the characters' voices truly became distinct. While yes, the writing was beautiful, for much of those beginning parts, the characters all seemed to have the same voice and could be rather interchangeable. It also ends rather abruptly, which was a bit jarring. It leaves no room for doubt that it's not a standalone at least.

As a whole this is a fantastic modern epistolary novel filled with diversity and inclusion; for example, same-sex relationships aren't commented on; they just are. It's a book that also works wonderfully in audio and almost gives a totally new experience. It's a novel of love (of all kinds), loss, and mystery. And it's one to read if you're looking for something slightly charming and slightly thought-provoking.

This book managed to make me nostalgic for a time and place that have never existed. I loved watching the relationship between E and Henerey unfold through their letters and equally enjoyed watching their siblings find out more about them. I also really appreciated the author's approach and portrayal of E's OCD tendencies, which felt real in a way that can be unusual to find in books. The world building was very interesting and I'm curious to see how things progress in the next book. This was a fast, fun, and touching read that I've already recommended to friends.

Whimsical, aquatic, epistolary, neurodivergent! Just a tad slow - this one rewards a reader who appreciates language and isn't looking for high-speed action.

I found this book a little hard to read and get into, but towards the end I did start getting interested and I think it started to come together in a way that I was like "what?!", but it felt like a slog up until that point.

A highlight was the the romance, and I could really feel the chemistry and yearning for connection and anticipation. I think also the deeper (heh) you get into the book and the more used to the writing you get, you can finally be a little in awe at the worldbuilding because this world is really cool and interesting! Overall, I think the biggest problem is that, to me, all the letters had similar "voices" and often it was just written a way that was unfriendly to my brain. I think this is one where an audiobook would've helped, but just eyeball reading did feel a little painful.

Thank you to Orbit for the ARC!

A fantastical multiple POV tale that takes us deep into the ocean. The audience is introduced to our characters and world through letters and other forms of communication.

This is so long overdue, but: how are people not all talking about this book?!?!!?! It’s received zero press from what I’ve seen, but this was so enjoyable! Told entirely in epistolary form from the POVs of a slew of characters, this underwater story of academia and mystery was such a lovely world to fall into. With queer storylines, endearing romance, heartwarming friendships, mysterious histories, and representation of anxiety in ways I haven’t seen with such accuracy, this book had me riveted. E is a protagonist I was rooting for so intently, and Henerey is such a lovable and gentle MMC. Sophy and Vyerin are the best sibling characters to round out the central cast, and I am so eager to see where the second book takes us with the cliffhangers we have been left with. Plus, I must add, the audiobook narrators of this book are fantastic and deserve all the applause and love possible. 4⭐, definitely give this a read!!

*Thank you again to NetGalley and the publishers for this ARC in exchange for an honest review.*

CW: mentions of/implications of death

Oh myyyy goooodddddd, I loved this book. I loved it so much. I loved the magical/underwater academia vibes. I would expect nothing else from Orbit, though, they haven’t missed as of yet.

I loved the family relationships in the book, a lot, not only does E.’s grief feel natural over losing her sister in the first pages of the book, but the author makes us believe in their relationship. She established their relationship through letters. I also LOVE their names, E refusing to share her full first name because her name is that bad, AND her sister being named Philosophy and her brother Arvist.

Sophy and Henrey were adorable in their letters, and it was honestly a gut punch every time I read about the way E and Viyern were coping with something so awful. Each of the characters feel fully realized, fully developed, and have motivation make sense.

The world building was STUNNING, as was the writing, they both leant to a really great atmosphere in the book.

I listened to this on Audibook, as well as reading my e-galley and a physical book, I highly recommended the audiobook

I also liked the commentary on politics and academic bureaucracy, it was a really fascinating way for the author to dissect some of the problems with academia. And that plays a direct role in the plot and in the motivations of E. and Sophy.

Also, casual queer rep! Viyern is married to a man and E is married to a woman. I ADORE the way they just made it something out in the open and not a main focus of their personalities or plotlines. The book was about death and grief, not about homophobia. The book also features non-binary characters, and just like with the queer characters, the identity isn’t focused on so intensely.

I also love how literally EVERYONE acts like they’re on the spectrum, how iconic of Cathrall to do that.

The way that the relationships of a romantic nature were realistic and domestic, the characters cared about each other, challenged each other, and showed each other love and compassion. Both Viyern’s husband and E’s wife practice a lot of support with their grieving.

There are multiple time jumps, and in my opinion, it’s incredibly difficult to pull it off, but Cathrall DOES. She manages to keep it from being too confusing, and the sisters and brothers communicating in the past establish care for the characters.

AND THE WAY THAT THEY TALK ABOUT THEIR SPOUSES TOGETHER? Oh, it’s SO SWEET. I love the two of them, I love how the relationships were portrayed and just how functional the relationships are.

I also loved the portrayal of male insecurity in an academic and personal setting, while E. struggles with it, it’s refreshing to see it on a male character.

I thought the pacing was well done as well, the mystery unfolded in a fun way,

And the *ending*.

I loved the book so much.

My god.

Can’t wait for book 2!

*3.5 stars*

i received this as an arc last year, and somehow didn't get to it until now, but this light underwater academic mystery was exactly what i needed last week! and the cover!!!

very cool and unique worldbuilding in this: an amphibious society centered around academia. i love an epistolary novel and thought the correspondence romance and quirky characters were very sweet. i didn't find the characters had very distinct voices, but maybe this is accomplished better in hard copy with different formatting.

this was quite slow-paced, i wasn't fully invested in the plot until halfway through and it really doesn't pick up until right at the end - but what does happen at the end was worth the wait! i do think it could have been ~50 pages shorter and the excessive parentheticals irked me.

definitely look forward to reading the second half of this duology, which is releasing later this year. thanks to the publisher and netgalley for the arc!

3.5

This is such a fascinating debut! It's cozy-ish and character driven and told entirely in letters and sections of documents, Cathrall creates a world where nearly everyone lives underwater. A year ago, there was a tragic accident where E. and Henerey disappeared and now we follow letters between their siblings (Sophy and Vyerin) trying to solve the mystery of what happened.

The world is fascinating, and I loved thinking about the technology that would be required to move humanity underwater. I also loved the casual queerness and neurodiversity here. Both Sophy and Vyerin are happily married to people of the same gender and both E. and Henerey are neurodivergent. E.'s agoraphobia in particular was so well described and really hit home for me.

I think I did this book a disservice but listening to the audio, and I struggled at times to keep the characters straight in a way that I might not have if I read it with my eyes. I am intrigued in where this duology will end though, so I am thinking I will reread it physically before the conclusion comes out this spring.

The story is told mostly through correspondance. It takes a lot of talent to be able to work in that limited confine. It's charming to watch two families who have lost someone get to know their loved on'es signifigant other. As the story progressesa and we find out more and more it becomes apparent that something else might be going on. It sinks it's hooks into you and doesn't let go.

This one really wasn't for me.

Letters shared between two sets of pen pals detail an eventual love story between the reclusive E and her scholarly friend, Henery Ciel. after an earthquake destroys E's underwater home, her sister Sophy and Henry's brother, Veryin start their own written friendship trying to piece together the mystery of their siblings disappearance.

It could be that the whole epistolary genre isn't for me. I found the story got lost in the minutiae of the letters and I wasn't engaged with it at all.

It also could have been the language. A Letter to the Luminous Deep is written in highly formal academic language, perhaps even Victorian-esque in nature. I understand why it was done that way. It was about world building. It was about context. In a world dominated by anxious scholars and academic papers, the prose made sense. To me, it felt stilted and far too formal for the type of letters that were being written.

What did capture me was the world created. Perhaps it's because of the cover of the book but the whole idea of a book taking place solely in a community under the sea captured me with visions of bright, beautiful underwater depths balanced by dark, mysterious corners and isolating vastness. I pictured scurrying schools of fish and vibrant coral, almost comical submarines and intricately designed homes but also felt the loneliness of being surrounded by nothing but water for miles. Points for atmosphere for sure.

While it did pick up around the 80% mark and end on a bit of a cliff hanger, I probably won't be inspired to read the next book.

This book was very unique and scratched a deep sea itch I didn’t know I had! I’m glad I got the opportunity to read it. Thank you.

I gave this book two tries and I think the writing style just did not work for me. However, it is a fascinating idea set in a wonderful new world. and the epistolary nature did appeal. I may try to read it yet again because Austenesque writing has worked for me before, and expect to find it a gem!

I struggled to get into this book. I started it many times, only getting about 15% in. The book does pick up, and become more interesting. I feel like adding a journaling component not just letters did help drive the plot as well. I am actually interested in what will happen in the next book, even though I didn't particularly enjoy this one very much. I feel like there was a lot of background in this one that could set up well for a nice little adventure in book 2.

Thank you to Orbit Books and NetGalley for the eARC in exchange for an honest review.

The cover of this book is absolutely gorgeous. It was illustrated by Raxenne Maniquiz and designed by Charlotte Stroomer.

This novel is epistolary, which if you know me, you know I love. It’s told in letters between various parties.

I absolutely loved this book. The prose was just gorgeous, and the story and pacing were excellent. I loved the characters so much. I will absolutely be reading the sequel.

An utterly charming epistolary fantasy set under the ocean, exploring a penpal romance and the aftermath of a catastrophic seaquake.

This book follows reclusive E., who lives in a rather famous house in the deep sea, and scholar Henery Clel as they become pen pals and, ultimately, more. Set in the present day, E. and Henery's siblings piece together the origins of E. and Henery's relationship, tracing their romance through letters and journal entries left behind.

This book was a little bit slow, and I can understand some of the reviews that recommend it be about a third shorter, but ultimately, I feel the world-building was worth the extra words. There is an elegant nature to the writing, reminiscent of reading Jane Austen or a Victorian novel, which is very pleasing, and while this is the definition of a slow-build romance, it was lovely. Perfect when you're in the mood for a quiet yet atmospheric read set in a well-formed world.

Side note, I got to meet the author at an event shortly after the book was launched, and she was delightful.

Thank you to the author, NetGalley, and Orbit Books for the opportunity to read this book.

A charming, whimsical, and deeply imaginative gem of a book. I found myself caught up not only in the mystery of the depths, but in the various interpersonal dynamics and relationships at play - professional, romantic, familial, or friendly. As original and beautiful as the undersea world it depicts. I'm having a hard time not writing like the fanciful letter-writers of the book itself (it's stylistically alluring, to say the least), and I can't wait to read the sequel!

Thank you to the publisher for the advance copy in exchange for an honest review.

A Letter to the Lumious Deep is an epistolary novel. The letters are presented from two timelines. The first is between E. and Henerey-- E. discovers an interesting sea creature outside her window and reaches out to renowned scholar Henerey to inquire about it. E. and Henerey end up becoming pen pals through this exchange and a romance blossoms between. However, they both have gone missing, so the other set of letters is an exchange of their siblings, Sophy and Vyerin. Sophy and Vyerin gradually learn about the blossoming relationship of their sibling through discovering the letters left behind, and are working to piece together what happened to them. The novel switches back and forth between E.'s and Henerey's exchanges and Sophy's and Vyerin's.

The writing style combined with the epistolary format did not work for me here. I enjoyed two other recently published fantasy romance books that involve characters exchanging letters, but those books both had very distinguishable voices between the characters, and also involved the traditional exposition-way of telling a story. This was all letters, and I found that all of the characters sounded exactly the same. I had a hard time telling them apart. The style also involves every character using a large amount of parathesis. It's a little funny to me because I find myself using paratheses a lot in my own writing. It certainly adds character to how one thinks/speaks, but at the same time parathesis are typically included as additional information that is not actually needed, though should be helpful. The fact that all characters did this in every letter was too much. I think it would've helped better distinguish the characters from one another if only character wrote in such a fashion. I also struggled with the timeline aspect. It flips back and forth between the past (E. and Henerey's letters) and the present (Sophy's and Vyerin's letters). Combined with not being able to tell who is who, I gave up on this one.

I think this book will be popular with readers who really love episolary novels, and especially if they want one with overlapping timelines. It's good for readers who like to figure things out on their own, don't mind being thrown directly into a story, and require less hand-holding.