What a fun read!!

Lighthearted and magical, this proves that academia really is my genre 😍

I loved the adventure and the underwater theme throughout, it still had a proper cosy feel to it as well!

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. But the style and the two mysterious main characters, E and Henerey, are so suited to my reading personality that my hangups with the ending didn't really affect my love of this, and that remains the case now I've re-read and relistened to this first instalment. I can't wait for the sequel!.

An underwater fantasy told entirely through letters, two people try to uncover their siblings' disappearances.
I loved the format of this. Cathrall did an amazing job piecing together character and plot and worldbuilding through the epistolary format, with vivid descriptions of the book's aquatic world being perfectly developed and not overwhelming or lacking. I enjoyed following the story along as it built up, and the characters were relatable and likeable and made this a thoroughly enjoyable read.

I really struggled with this book. I wanted to love it as it seemed like it had lots of interesting things but I feel like the writing was difficult to get through at points.

I enjoyed the characters and their relationships but found it difficult to stay interested in the plot.

Thanks to NetGalley and Little Brown Book Group UK for providing me with this arc

i wasnt sure on this book. it felt a bit fantasy. a bit harry potter ish. a bit hit miss magic but romance.
i didnt not like it. but im not a big sci fi magic bookish love usually anyway.
this book did have heart. and i really enjoyed getting to know the stories of our characters.
both got to know eachother through letters. the siblings had a romance in both the timelines so it felt we were getting to know lots about the romance not just the mystery surrounding the disappearance of two of our romantic leads.
their is grief shown in this book. and i think the letters made that more personal and you could really feel the feelings. and also how it bought the characters together more.
im not sure on this book. but im eqaully not unsure! because i cant put my finger on anything that made me not like it. yet it has quenched the thirst i had from reading the blurb and the beautiful cover.

Sadly I didn't make it to the end and I genuinely am sad because from the blurb this story had all the things I love - the sea, academia, the underwater house, exploration and so on. But the writing fell a bit flat for me and the overuse of parentheses killed it. I found half my attention focused on counting how many times they were used on each page instead of being wholly on the story - one page alone had 6 pairs!
Also, I wasn't sure whether this was a dystopian version of earth, or an alternative version of earth, or a fantasy world, and when I can't immediately ground myself in place and time it leaves me feeling as though I'm missing a piece of the story.

This one is a lot easier to review than to rate, so take my stars with a grain of salt.

A year after they've lost their respective siblings, Henerey and E., Sophy and Vyerin start writing to each other and exchanging H & E's surviving correspondence. As they do so, they develop a lovely friendship, witness their siblings fall in love in their letters, and discover a mystery...

There is nothing mediocre about this book, it is absolutely an original.There are aspects I really loved and aspects that really didn't work for me, but very little that fell in the middle. The plot, worldbuilding and relationships between the characters were all really really good. The author creates a beautiful underwater world filled with scholars (and painfully accurate university politics). The relationships between the characters were very nuanced and I loved watching their relationships slowly develop. The mystery was intriguing and unexpected, and by the end Of the book, I was absolutely hooked.

Unfortunately, the one aspect that didn't work for me is kind of a big one: the narration. The entire story is told as correspondence. The letter writing style is on the formal side, and while this makes sense for the story, it doesn't help the reading experience: it doesn't make for the most accessible reading, especially as it means the characters' writing voices are stylistically similar. Initially, I found it more impressive than enjoyable, if that makes sense. This did improve as I got to know the characters and their letters become more informal.

By the end of the book, I was invested enough that I will absolutely be reading the sequel. Or well, I'll be listening to it. Apparently the audiobook has multiple narrators, and I suspect that will make a huge difference to the reading experience! (I'll report back once I've confirmed this suspicion)

Many thanks to Little, Brown Book Group and Netgalley for letting me read an eARC of this title.

4 stars

This book is a great blend of epistolary storytelling, deep-sea exploration and cute relationships. A letter to the luminous deep is a beautiful book with an immersive world-building filled with oceanic wonder and a sense of discovery that feels both scientific and deeply personal.

The heart of the book lies in the letters, which unfold a story of mystery, longing and connection. The characters are well-developed, with emotional depth and quirks that make them feel real, and the romance is a slow burn. I really liked that!

The reason for the four stars is the pacing from this book, which can be slow at times.
However for those who enjoy lush, poetic writing and a quiet, thoughtful fantasy, this book is a treasure worth diving into!

Highly recommend this book if you are a fan of gentle fantasy, deep-sea adventure and epistolary books.

Thank you Netgalley for providing me this arc in exchange for my honest opinion.

would like to express my gratitude to NetGalley and Little, Brown Book Group for providing me with a copy of this enchanting, cosy magical academia read! I thoroughly enjoyed the unique format of the book, presented in the form of letters, which added an element of liberation and intimacy to the storytelling. The easy-to-read style made it a delightful experience, and I appreciated how the narrative unfolded over an extended period. The slow pacing allowed for deeper character development and immersion in the richly crafted world. Overall, it was a charming journey that I relished from beginning to end!

This one had so much potential—an epistolary novel about deep-sea exploration, mysterious creatures, and a nerdy romance? Yes, please! But sadly, A Letter to the Luminous Deep didn’t quite deliver. The romance between E and Henry is adorable (think “talk nerdy to me” vibes), and the mental health rep is spot-on. But the plot? Barely there. It’s all letters—beautiful, flowery, and exhaustingly verbose—with little action or world-building. The underwater world is barely described, and the pacing is glacial. The last 5% tries to save it, but by then, it’s too late. Gorgeous cover, sweet romance, but not enough substance. If you love slow, character-driven stories, you might enjoy this. Otherwise, dive elsewhere. 🌊

Thank you, NetGalley and Little Brown Book Group UK for an ARC in exchange for an honest review.

#ALettertotheLuminousDeep #NetGalley

I want to love this book. On paper it has everything I could want in a story, but I just cannot seem to get into it. So unfortunately for now I believe I have to DNF this book. It’s a soft DNF I think I might come back to it as an audiobook at some point because a part of me still thinks I can love it.

Dear friends and Goodreads readers,

I am writing to draw your attention to the lovely cover of the debut novel by Sylvie Cathrall, "A Letter to the Luminous Deep," which is the first book in The Sunken Archive series. I also want to sincerely apologize for not give a damn what will happen to the letters, I mean this book—letters from a few characters that I am not even sure if they are people or perhaps mermaids.
I’ve started to think that I don’t have any idea what’s going on. The cozy romance, academia, and love of letters didn’t pique my interest. I wish the author the best of luck; I’m sure this is just me, and others will find it more interesting and unique in their own way.

Sincerely,
Shirin

P.S. I want to express my thanks to Little, Brown Book Group UK and NetGalley for DRC. I didn’t rate it here on Goodreads because I didn’t finish the book, but I felt I needed to give a star rating for feedback.

I was so excited to read this book. The synopsis was so interesting, the premise of a mystery at sea and the way it was described with the 2 sets of characters and wrote through letters left me really curious.
Sadly as the letters kept going I started getting confused with the many letter POVs and also the scholar language that was used. I pushed through it a little while but, unfortunately I had to DNF the book. I just wasn't for me😔
I'm so sorry. You gave me the chance to read and I just couldn't get with the writing and the language.

If you love academia and fantasy books, then you will love this one! I adored that it was so unique and set in an underwater world, and somehow it was so cozy too. The timeline changing was a little hard to follow at times, but nevertheless it was a fantastic debut. It was heartwarming and wholesome, and I loved the characters.

“Reading your letter was an experience like no other. Have you ever considered, E., that someone ought to write a Fantasy about you?” :’)

A Letter to the Luminous Deep was an enchanting and unique read. It was the first epistolary novel I have come across, and after getting the hang of it, I really enjoyed it and found the style enhanced the story. The characters were exceedingly well written, and the mental health aspect was portrayed so thoughtfully I found it helped negate the distance I was worried I would feel from the writing style. The prose was whimsical and romantic (my FAVOURITE part). Overall, I had a great time reading this book and recommend it to fans of Emily Wilde, A Feather so Black, and cozy, otherworldly fantasy. Sylvie Cathrall succeeded in creating a vivid underwater world that I cannot wait to return to in the sequel.

Thank you so much to Little, Brown Book Group UK and NetGalley for providing me an early copy to review.

This cover is gorgeous and I was drawn in because of that and because it is written as letters between two people. Letter writing is a wonderful thing though sadly it is falling by the wayside nowadays. I have read a few books written this way and I find it enjoyable. And I did enjoy this story with its setting on some mystical water world set in the future, but also a bit of past, due to lost technology and reinvented items so that these people could survive in the depths of the oceans after a long ago great fall from the sky.

With letters and communications between Sophy and Vyerin as they search to find out what happened to their siblings E. and Henerey, uncovering letters sent and received hinting at a long held secret relating to the Deep House where E. resided. Excitement but also comfy because of the letter format making it a meandering uncovering of the truth by grief ridden siblings and I enjoyed how the chance letter that E. sent to Henerey led to a sweet little friendship and then romance between two people so well suited to each other and how it will change the future, even after their disappearance.

Really looking forward to seeing what the next book holds, after all that was found out by Sophy and Vyerin and I really hope that they can find E. and Henerey!

I had high hopes for this one, especially since I love epistolary romances, but unfortunately, I ended up DNFing it. That’s not a reflection of the book itself, just a case of it not being the right fit for me. It reminded me a lot of Emily Wilde’s Encyclopaedia of Fairies, which I enjoyed, but this one felt a bit too stiff for my taste. Maybe I simply wasn’t in the mood for it. That said, if you enjoy stories told through letters and are drawn to fantasy and folklore, this might be a book worth picking up!

This book was like slipping into a warm, enchanted tide pool - gentle, immersive, and brimming with hidden wonders. The underwater world-building was stunning, with its magical academia and delicate social intrigue, creating an atmosphere that felt both whimsical and grounded. The epistolary romance added such a tender charm, slowly unfolding through letters that were equal parts intellectual curiosity and heartfelt longing. It’s the kind of slow burn that sneaks up on you, leaving you completely invested in these anxious, kind-hearted scholars.

I adored how the story balanced its cozy, introspective tone with moments of mystery and discovery, and the nosy, loving families added a lovely warmth to the narrative. If you’re a fan of thoughtful, atmospheric fantasy with a dash of romance and a lot of heart, this book delivers beautifully. I already want to dive back into this world.

DNF.

The last thing I want to do after a long day of work is sit down and read this book that feels like I need a masters degree to understand.

The first ten minutes of reading is a huge information dump, it feels like someone threw a thesaurus at it and as you continue it doesn’t get better!!

Like all books it takes time to set the scene and explain the story but this felt like hard work!!

I hate DNF and I rarely do it but I just can’t continue, I’ve never put a book down so fast.

I have no idea what’s going on, who anyone is and absolutely nothing about this book made me want to keep trying. Very disappointing because the description sounded great and the cover is beautiful…. But my time is worth more than struggling through a book I don’t enjoy and I will not be attempting to continue this.

Thank you to NetGalley for an ARC copy of this book.

So, I’ve read this before but totally forgot and requested it a second time in preparation for book 2’s release.
My original review: “An epistolary romance set in an underwater world with magical academia? I was so ready to dive right into this. However, this light academia romance isn't quite for me, but I am giving extra stars for the cover alone. I really wanted to like this book but I could not get into this style of writing. I found myself quite bored and thought the pace was really slow.”
My updated review: I’m a moron — okay not actually, clearly my tastes have changed. I really enjoyed this. The multiple timelines being told across these letters was super fun and I think it was done really well. I’m still in love with the cover and I finally managed to get a copy of the Fairyloot edition which will be here TODAY (so excited!!)