3.75 stars

A Letter to the Luminous Deep is a debut underwater fantasy with a mystery. The story is told through letters and other media, which is something I particularly love to read. I felt the pacing of the book was quite slow and required more concentration than the average cosy fantasy, as you are required to piece the story together through various character's letters from the past as well as letters between the two present-day characters who are trying to find answers. There is also a lot of academia involved which might make it a bit more difficult to get through. However, the romance was sweet and there was great queer representation!

I listened to the audiobook which helped with keeping up with all the letters and who was writing what - the voice actors were great for this!

Thank you to NetGalley and the author for providing this ARC in exchange for an honest review!

This is one of those books I actually had to think long and hard about after finishing it because I was so conflicted over how to rate it, since there quite a few things I enjoyed but also at least as many I was frustrated with.

Starting with the positives, I was immediately hooked on the premise for this book: a light academia epistolary underwater fantasy mystery romance sounds like a mouthful, but also exactly like the type of book I would enjoy. Told entirely through letters, the book revolves around the disappearance of reclusive E. and scholar Henerey Clel following a mysterious discovery they made, and their siblings' attempts at making sense of this.

The relationships that develop between the different characters, which readers can witness slowly unfurling through their correspondence, were by far my favourite part of the book. Interactions between the different characters are realistic and rich, whether that's the sisterly relationship between E. and her Sophy, the budding romance between Henerey and E., or the friendship between Sophy and Henerey's brother Vyerin, bound together by grief and the need for closure. It is hard to convey such deep levels of human connections only through letters, but the author did a wonderful job of it.

The world is also intriguing and lavishly built, with many natural wonders and sea creatures being thoroughly presented throughout the book as the different characters engage in their research, and I was keen to learn as much as possible about them. What comes across as less clear in the world building is the way society is structured and functions, despite references to academia and its structure throughout. Now, it is entirely possible that this will become clearer in the next book (or books?) in the series, since this is only the first one - something which I realised very late on, as for some reason I was convinced I was reading a standalone.

What I struggled most with in reading this book were the writing style and the pacing. As the characters are all scholars or researchers, their use of language reflects this, with a prose reminiscent of Victorian English laced with academic jargon. This isn't typically an issue for me, since I'm used to reading academic papers for work, and I enjoyed other books written in a similar style: for instance, Emily Wilde's Encyclopaedia of Faeries is narrated through research journal entries and I had a great time with it. With A Letter to the Luminous Deep though, the sparks just didn't fly, and I ended up finding the style verbose and overly weighed down by unnecessary formalities, even in letters between siblings.

I was also completely unable to distinguish between the different voices, as all the characters sounded exactly the same in their writings. At one point, I had to switch to the audiobook version (which is excellent, by the way), as the production featuring multiple narrators finally allowed me to understand whose letter I was reading without constantly having to go back to check. This made me feel as though the book was just dragging along, something which wasn't helped by the extremely slow pace. Now, I generally prefer character development to plot so maybe this was a case of me reading this book at the wrong time, but I really struggled to get through it for large sections in which it felt as though nothing at all was happening. And then, everything happened all at once, ending on a pretty huge cliffhanger, which I found pretty frustrating.

I think I'll probably pick up the next book in the series since I am somewhat curious as to where the story might go next. This is also a debut and I see some great potential for the author in the next books, especially given how the relationships in this book were some of the best written I have come across recently. I also liked the queer normative society and the mental health rep (with depictions of OCD and anxiety), so there's definitely a lot to save here!

A Letter to the Luminous Deep beautifully blends mystery with light academia romance between two scholars on a quest to uncover secrets from unknown depths. I can’t remember the last time I read an epistolary novel—maybe back in school—so it was refreshing to see this format used in a fantasy novel.
I strongly believe A Letter to the Luminous Deep is one of those books best experienced in audio form; I thoroughly enjoyed the full cast narration.
This magical, underwater adventure will leave you hungry for more! A truly wonderful debut—I’m excited to see what comes next!

I was transported to a magical underwater realm by Sylvie Cathrall's exquisitely constructed fantasy, A Letter to the Luminous Deep, which is read aloud by Claire Morgan, Joshua Riley, Justin Avoth, and Kit Griffiths. This book skilfully combines enthralling mystery, epistolary romance, and mystical academia. The narrative starts with E., a solitary academic, initiating a correspondence with the esteemed Henerey Clel. A seismic shift alters everything as their correspondence blossoms into a profound and transforming love. A year later, Sophy and Vyerin, their siblings, use what's left behind to investigate the mystery of their abduction. Fans of whimsical, creative tales will find this to be an appealing read due to its rich world-building and poignant romance.

This was a cute story and I really enjoyed it though i did find it a little confusing at first especially with the multiple pov and differentiating between them

What a fun read. I am not normally into anything set with an academic backdrop but the main investigation plot line caught my attention. I was really invested in the different relationships that emerged as well as the (partial) reveal of what the academics have been trying to understand. Lovely representation of neurodivergence. Excited to read the sequel.

I really thought I would enjoy this book because of the synopsis but I didn't.
Unfortunately I was confused from the beginning and the writing just wasn’t very gripping
It may have been the letter format that wasn’t for me but it really didn’t allow me to know the characters deeply.

I truly enjoyed this fantasy scfi est book! This was such a fun audiobook to listen to especially because it feels like the logs we are listening to it was alot more intimate! I truly adore the way it felt to listen to this and feel so connected to all of the characters as well as the story you truly feel so connected!

am very hit and miss with epistolary novels, but I tend to love those that mix fantasy with history in a believable way. The biggest component is that the letter need to be describing something worth writing to someone about, not merely used as a device for exposition. Unfortunately, found this to be more of the latter type and lost interest in the story. I’m disappointed as I had been looking forward to this book for a long time but it just wasn’t for me.

extremely enchanting and captivating. I havent read(or heard in this case) a letter novel this mysterious and interesting before.
Exploring the budding relationship of E and Henry through their letters alongside Sophy and Henry's brother (i do not currently know how to spell his name), was an amazing experience. all the characters felt real, well thought out and deep as the oceans they explore They have entered my heart and it will be a good while before they will leave it again

more detailed review to come

Obsessed brilliant book about the deep blue sea
This story explores a range of emotional character relationships. The full cast audiobook adds vivid personality to the various characters whose letters make up the book. I really enjoyed this and I am curious to see how the story progresses in the sequel.
Enjoyed every minute of it

A delightful story of discovery and romance set in 1002 and told through the correspondence of each character, most notably E. Sidnosen to Henerey Clel. The prose is beautiful and works well with the writing format, which is part Magical Academia, part Deep-Sea Fantasy with a sprinkling of period drama elements in the letter writing.

The story begins when E.'s sister Sophy Sidnorjay and Henerey's brother, Captain Vyerin Clel correspond about their respective siblings' disappearance and the destruction of E’s family home, The Deephouse.

This is a very slow-paced, surreal and wandering tale which takes a while to come together, I did at times find it hard to follow with the number of characters but the cast of narrators did an excellent job and helped with that. I personally feel it could have been a little shorter. Overall a nice relaxing read. 3.5 rounded up.

This was a sweet, soft academia adventure with some really interesting world building - my only quibble is that I struggled to enjoy the epistolary form in an audio format but I'm looking forward to reading the novel to see how the two versions compare.

I was initially intrigued by this book because of the fact that it’s told entirely through letters which tickles my brain juuuusst right, and I was also curious about how the mystery and world building would play out in this format.

Wonderfully, as it turns out! The story may be told through correspondence, but it doesn’t lose any of the world building in the process. Both it and the characters are given so much depth and you can really get a feel for the world and how it came to be etc without any info dumping, just naturally included in the course of conversation and a few academic article extracts here and there.

There are so many little tidbits and clues both to the world and what happened to E and Henery scattered throughout which you can use to try and start piecing things together, but honestly I was still surprised by the twists! I was thoroughly intrigued and hooked into the story, even if I did initially struggle with keeping who was who and who was writing to who straight in my head!

Though I found this to largely be a problem with the audiobook that was more than likely just specific to me and my ADHD brain, because after going back and looking at it on the page when I was lucky enough to be sent a finished copy, it was much easier for me to keep up with everyone! I did really enjoy the narrator for the audiobook, however, and they kept the story engaging enough to help me through the slower parts when my attention might have otherwise wandered! I also think that I wasn't quite anticipating just how much attention I would need to pay to this when I first dived into the book, and I do tend to listen to an audiobook when doing housework etc!

ANYWAY! The thing I really appreciated about this book was not only the cosiness of it all but anxiety and mental health rep. I find it very rare to come across the former in books and I was delighted to come across it in this one and I personally think it was very well done! I also really loved not only seeing E and Henery’s romance blossom on the page, but also seeing Sophie’s with her wife as well as her friendship with Henery’s brother! It was heartwarming, especially as they were both still coming to terms with their grief, but they both made me chuckle too!

I did, however, want to throttle E’s brother more than once courtesy of how much I empathised with E and the fact that he really is a thoughtless dolt! I’m not entirely sure the ending makes up for it either, but we’ll see!

Either way, the mix of heartwarming bonds and mystery kept me hooked into the story despite the rather sedate pacing here and there! It’s not necessarily a bad thing, the scene needed to be set for their discoveries and the story and relationships needed to be built up, but it can be quite slow paced here and there. It’s a story that you really need to savour and pay attention to, or at least that’s how I feel considering all of the little details here and there!

Overall, I really enjoyed both trying to solve the mystery and watching both romances and friendships blossom amongst the characters! I loved the representation present throughout the book and the world was an intriguing one that I was always eager to find out more about! Luminous deep remained engaging until the end, with certain letters really managing to make you feel the giddiness of those first feelings of love between E and Henery as well as building tension here or there with a well placed word or thought from a character!

If you enjoyed Emily Wilde, then this is definitely one for you! It’s cosy, heartwarming and filled with wonderful characters and an abundance of mystery!

This is one of my favourite books I've read this year. Cathrall creates an immersive, expansive water-based world, seen through the eyes of many academics with wildly different approaches to life. Prepare to laugh at the oblivious nature of one character, laugh over the tongue in cheek academia references and jokes, while simultaneously crying about the effusive, beautiful relationship of the main characters as they bond over their shared loves and hardships. With queer, neurodivergent & disabled rep, told through an epistolary format, all tied up with an overarching mystery, I simply adored this book.

The narrators do an incredible job, really bringing to life their multitude of characters and making them feel distinct and fully realised. They put so much emotion into their voices, which especially with the lack of tone tags due to the epistolary nature of the writing helps to convey the humour and grief of the characters!

5/5, desperately curious to see how this series continues.

Sylvie Cathrall's charming fantasy transports readers to a magical underwater setting, complete with captivating academia and a heartwarming pen pal connection.

The characters are delightfully eccentric, and the novel is rich in atmospheric oceanic world-building and themes of found family. Cathrall's debut is a captivating read that will leave readers eagerly anticipating her future work.

Although, difficult at first to grasp, the epistolary format adds a fascinating dimension, allowing us to unravel the mysteries surrounding the protagonists' sudden disappearance as we delve into their scholarly correspondence.

4 stars

I listened to the audiobook of this enchanting underwater academic tale told through a set of letters between two different sets of characters.
I think the audiobook really enhanced my enjoyment as it so clearly differentiated between the different narrators. Each was excellent.
The book combines scientific exploration, light romance and a bit of mystery. The pace is rather gentle thanks to the nature of its letter based telling.

I loved this, slow-paced unfurling of a mystery and connections between two people who vanished and the family trying to piece together what happened.

Maybe it's the archivist in me,but the idea of close relations only really learning to understand their family, their thoughts and feelings, through what they left behind, the letters really spoke to me. I experienced this story both through an e-arc, and an audio arc, listening to the audio first before switching to the written version, and I hadn't read any spoilers about the book before, so didn't actually expect the epistolary format and kept waiting for the straight narrative to kick in, by the time I realised the plot and characters were going to reveal themselves entirely through letters, I was already in love. The narrators did such a good job (though my least favourite was the narrator for Henerey, he seemed to be playing it for the stage, a bit over the top and too many instances of placing emphasis on odd words in a sentence for me, like he was reading the words without having the full context of the sentence), Sophy was vibrant and clever and a great foil for her sister, the introverted E, and

The theme of discovery and exploration was really well done, and not just the exploration of The Deep, or the discoveries made there, but how the characters were explored and discovered through their correspondence, and how E and Henerey discovered each other and aspects about themselves that they didn't realise were there through their connection to each other.

Again, for those of you preferring quick romance, resolutions, or plot, this isn't it, it is a slow unfurling imagine gradually emerging sea creatures from a dark abyss, for a long while it doesn't look like there's anything to see, and then things start to happen, until the end when suddenly a lot is shown to us all at once. That is my one drawback, the reveals at the end came very quickly and conveniently, or maybe I should say inconveniently, because certain characters had inconveniently kept the answers to themselves this whole time, and annoyingly with the 'because you had to discover it for yourselves' excuse. (Oh and the fact that the e-arc at least had some mistakes in the dating of the letters, which didn't really help when the timeline jumped between two main time periods). But the style and the two mysterious main characters, E and Henerey, were so suited to my reading personality then, that I didn't really care.

A beautiful story in a watery world. Told through a series of letters, we hear of the story of E and Henery as their siblings try and understand their disappearance.
Its so easy to get close to these characters, I loved the rep of OCD and anxiety, its so nice that the point of this story wasn’t E overcoming anything - rather it was just a fact that she had it and the world, or rather her world, can adapt to that along with her. I was absolutely incensed at Artist, like I started to hate his character more than villains in like Malazan, which is honestly probably unfair but I stand by my feelings. These letters made me want to live underwater, set in this almost hopeful post apocalypse where land isn’t really a thing, here is a world fully on or below the water.

Covering two storylines, one covering the meeting of E and Henery and their investigation of the ‘mystery’ and the other is Sophy and Vyerin and their wish to understand their siblings that days and closest relationship. It starts out as a character driven fantasy/scifi but soon evolves into a mystery of the past and the future set in the luminous deep 🪼

Let's start with what I loved which is the fact this was written through letters. I loved how personal and intimate it felt.

I also enjoyed the writing style it was poetic and whimsical.

Now I know I said I loved the letters and I do but I don't think this was the right world for this style of book. This is set underwater but there is no world building and no sense of being underwater. I would of really like to experience that and as much as I love the letters I don't think it was the right setting. It's very easy to forget we are underwater.

I liked the characters and I especially loved the way Sophy's mental health was woven into the story. However I feel like all the characters sounded the same. There writing style within letters wasn't distinguishable from one another. I would have liked to have seen more individuality within there letters such as grammar quirks or catchphrases.

I also think this book is too long. The mystery is intriguing but the middle went at a glacial pace with no real development or anything happening... then to only be left on a cliffhanger which I felt wasn't needed.

There is an audience for this book but it sadly isn't me.