Thank you to NetGalley and Orbit for providing me with an egalley of this book to read and give an honest review. The opinions expressed here are my own.
This book is an underwater academia fantasy. Told through letters and interviews between the characters, you slowly learn the fate of E. Cidnosin and Henerey Clel as their siblings correspond and piece together their ultimate fate.
What initially drew me to this book was the cover. It is absolutely gorgeous. And then when I read the blurb I was truly interested to see how the author would tell an underwater story. I love books of academia, especially when fantasy is involved. What I was not prepared for was the format!
I was unsure if the format of this book would make me dislike it. I've never read an epistolary tale before. There's no real dialogue between the characters save for their correspondence and what they deem necessary to tell of dialogue within those pages, and a few interviews we see from one of the researchers. It seemed like it might get quickly boring or annoying. But I ended up truly loving it. The unraveling of the mystery is a slow burn with most of the correspondence being very poetic and long in prose. And the epistolary style gives us multiple PVS throughout the story. I loved how the characters seem even more open than they might be in person to give personal details, voice their fears, and find solutions with words written on paper. I really enjoyed how the author chose to use the letters, interviews, and book excerpts to show us the story of E and Henerey. The letters do a nice job of showing E's anxiety, OCD, and her unease with interacting with people in person. We also get a good view of Henerey's anxiety. Plus we see how charming both Sophy and Vy are and how their vulnerabilities have shaped their friendship.
The world building is quite interesting. Almost the entire book takes place with the characters living or researching underwater. The characters for the most part are all academics in some way: artists and researchers. The author does a nice job of forming the visual of the world through the letters we read. I loved the little things she inserts to show us how the characters have adapted to their surrounding: water proof paper being the most obvious of adaptations for people living and researching underwater! At the same time, I don't feel like the author truly shows us how this world came to be. She mentions a sky world quite a few times and how it fell, but I never truly got a sense of why or how this world came to be.
Overall, the characters development was quite nice. I loved watching E and Henerey's letters and how they slowly become connected and find some romance. I also loved how Sophy, E's sister, and Vyerin, Henerey's brother, form a friendship through their letters and their sharing of information with each other. Cathrall also takes great strides to be diverse and inclusive in this book.
If you've not read epistolary writing before, I'd give this one a try! It was different from anything I've ever read before. It's an enchanting tale of anxious people!
This book indeed ends on a bit of a cliffhanger leaving you wanting to know just exactly what the characters have found and how they might go about saving those they love. I'm definitely intrigued to read the follow up and see where it goes.

My first ever approved ARC was unfortunately a DNF for me. Maybe that isn’t even fair to say. I can see myself trying again in the future, because I so badly wanted to love this book. I still believe it deserves its moment, and could be such a win for someone else.

The cover drew me in instantly with its beautiful & bright colors (I love a good underwater scene). I was intrigued by the story and the thought of a light academia fantasy set in a magical underwater world. Sounds amazing right? I’m just not sure the epistolary format was the right choice. It just didn’t work for me, and I wish I could read it another way. I felt the voices of the characters were far too similar, which made it difficult for me to remember who’s letter I was reading, which then led to flipping back and forth, and I was just not, making, progress.

That all to say, take my thoughts & ⭐️⭐️ with a grain of salt. I’ve seen many 4.5-5 star reviews out there, they just didn’t resonate for me. The writing is not bad, the story is there… who knows, maybe it will be your next favorite! It’s out April 23 and would certainly, if nothing else, look damn good on a shelf.

A beautiful book written in epistolary, it’s both whimsical and intellectually written. The letters between Henry and E are intimate, yet formal. It drew me in and was so poetic and flowed well.
The world building was stellar, snd so unique! The underwater atmosphere was very reminiscent to Bioshock, one of my favorite game series ever. I loved it!
This book was such a unique experience and despite the slow burn format, it was so hard to put this book down. Each of the characters had such depth and felt very well written.
If you love anything cozy, slow burn romance, light academia, mystery.. this book is definitely one to pick up!

A big thank you to NetGalley and Orbit books for an ARC! (with my honest review) this book was truly an enchanting experience and can’t wait to read the 2nd installment of The Sunken Archives!

(Review will be posted on Goodreads on 25th of March, 30 days to release)

A bit hard to get going as it is written in epistolary form using formal language. But once you get into the heart of the story/mystery it’s really enjoyable! Love the sci-fi elements and the two sets of main characters. Can’t wait to read more when the second one comes out!

I was absolutely ENTHRALLED with this book. The more I read, the more invested I became. In the characters. In the world building. In the story. In the mystery. So beautifully written, I think the epistolary format fit this book really well, and made the story progression really interesting.

The story felt like a cozy, whimsical, enchanting mystery set at the bottom of the ocean. I really enjoyed the romance, and was cheering E. and Henerey on the whole time. It was also really nice to see the various friendships between characters develop. All the characters were just really well done, and felt endearing and fleshed out.

I loved this book so much and cannot WAIT for the next one to see how this story concludes!

This incredible book took me completely by surprise. I was not expecting to love it as much as I did! From the beginning, this book pulled me in with its letter format, a tense mystery to solve, and its beautiful (almost academic) writing. The story, the world, the writing, and the characters were all utterly unique to me, and I was intrigued all the way through.

Sometimes there's a risk in writing all letters—risk of losing important information not included in letters, risk of readers' boredom, etc. However, Sylvie Cathrall is an absolute expert in how she manages the format. There's extensive world building to understand, and she utilizes letters to do it in a practical way. I also found the tension to be strong throughout with gathering evidence towards solving a mystery. And the characters! I love that we got all their points of view through letters.

This first book in the series sets itself up for massive potential. It has all the science-academia vibes with a breathtaking underwater world and a hint of fantasy/sci-fi/dystopian all rolled into one. There truly is no other book like this one! I can see how some people wouldn't like it with its more formal, academic writing and slow set-up. But if you give it a chance, it has the chance to captivate you and take you for an unforgettable ride.

Writing Aesthetic/Style: 5
Plot/Movement: 5
Character Development: 5
Overall: 5

Thank you, Orbit, for the arc!
Releases April 23, 2024

Trigger/Content Warnings: near drowning, tense underwater scenes, death of family members

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

I wanted this to be an epistolary Emily Wilde, and while it was entirely epistolary and shared similar prose and scholarly language to Emily Wilde's Encyclopaedia of Faeries, I was bored. Very bored. So bored that I had to put it down for now.

I really struggled with the letters. This story is entirely epistolary, and all of the characters sounded the same in the letters. I would have been more likely to push through had the voices each been more distinct.

I'm so heartbroken this didn't work for me!!

This was such a fun fantasy. I loved the letter aspect and the under the sea vibes. It was just a cozy, fun time. I would definitely pick up this author again in the future.

This was my first epistolary read and it was very well written! It is a slow read and just when things get interesting, you have to wait until the next book!

When reclusive “E.” finds a bizarre structure growing in her garden outside her underwater home, she begins a correspondence with scholar Henerey Clel to solve the mystery of what is in her garden. As the two write letters, they strike up a friendship and maybe even more. Not long after, an underwater earthquake results in E. and Henerey’s disappearance. The book takes place a year later, following E.’s sister Sophy, and Henery’s brother Vyerin as they try to piece together letters between their siblings, and determine what exactly happened to their missing siblings.

This book features:
- Cozy fantasy/mystery
- Epistolary story
- Portrayals of Anxiety and OCD
- Oceanic atmosphere
- Academia
- Slow slow slow burn strangers-friends-lovers
- Queer marriage (side characters)
- Some big vocab words


This was a 5⭐️ read for me. I loved everything about this book. The cozy underwater vibe, the mystery, the love story. The development of relationships between all of the different characters was so beautiful and realistic. The settings were beautiful and imaginative. This book was cozy but also an intriguing mystery that comes together into such an exciting and fun conclusion. The characters were all dimensional and the sarcastic comments and humour were so entertaining. I absolutely devoured this book. I cannot wait to get my hands on the physical copy, and I will be desperately awaiting book two. I truly will be thinking about this book for a long time

Unfortunately this is a DNF for me at 20%, I just can't get into the story! I'm disappointed as I was really hoping to love this, especially with the comparison to Emily Wilde, but it was just *too* slow for me and I couldn't get past the narrator😅

Thank you to Orbit Books for providing me an ARC through Netgalley in exchange for an honest review!!

A Letter to the Luminous Deep has my entire heart, body and soul! I've never felt more represented by a book in my life! My anxiety has always been a huge struggle for me. Much like one of our main characters, E, my anxiety has kept me a prisoner in my own room on my worst days. The way Sylvie writes about E's struggles was almost like she had walked into my mind and pulled my anxiety right from my brain and onto the paper. It was Syvie's writing of E that made me feel so connected to the story and has given it the number one place in my heart.

Luminous Deep is written in an interesting way. It's told through a mixture of past and present letters, newspaper clippings, and voicemails. It is such a fantastic and unique way to tell a story! Luminous Deep is about two scholars trying to figure out their sibling's remaining days before they mysteriously disappeared. In fact, almost every character in the book is a scholar in some way. The way the letters and other media are written does a fantastic job of portraying the world all these characters live in. I felt like I was actually a part of their world, digging through old letters with them myself!

If all of this doesn't convince you, then the magical underwater world filled with lush descriptions will be icing on the cake! As someone who loves marine biology and is in the process of getting a biology degree, I was absolutely in love with the marine theme. A Luminous Deep morphs from one mystery to the next. Sylvie has written this book fantastically! I wasn't able to predict anything! As a final note, it is not openly stated anywhere, but this book does end on a cliffhanger and will have a sequel!

A Letter to the Luminous Deep was an engaging, cozy, and thoroughly enjoyable read.

When reclusive E. witnesses a strange creature outside her underwater home, she works up the courage to pen a letter to Scholar Henerey Clel to inquire as to his thoughts on the matter.

This epistolary novel explores letters between E. and Henerey as shared and read by E.‘s sister and Henerey’s brother in an effort to work out what happened to their vanished siblings.

I absolutely loved that not only do we get to experience the friendship and love that developed between Henry and E., but we experience their sibling’s budding friendship while Sophy and Vyerin try to uncover the mystery of their sibling’s disappearance as well as recounting fond memories of their respective family member.

I can see fans of the Emily Wilde series also liking the academic oriented letters that are exchanged between the characters.

Thank you so much to Netgalley for a copy of this ARC in exchange for my review! With that being said, this is me sharing my unbiased thoughts about this book. The setting and the delivery of the story is very cool and different. Everything occurs underwater (with humans!) and the entirety of the novel is told by pen pals via letters. I had never read a novel written in this way and it was an interesting experience. With that being said, the language in the novel was very academic. This made reading and digesting what was happening a little difficult. I think that I spent about 25% of the book not understanding what was happening because of some of the dialogue. The story sets a lot of ground work for the rest of the series and I’m really excited to see where it goes!

2.5/3 stars

I had a really difficult time getting through this book. I, like many others it seems, was so excited for this book as it was compared to the Emily Wilde series. First, it was completely my fault for not understanding what an "epistolary" novel meant. Honestly, I was excited about the letters, but I couldn't get past the language - formal, flowery, and almost like someone word-vomited all over their letter. I was enticed by the underwater world and the mystery around our sequestered underwater inhabitant and the marine scientist. However, that mystery in and of itself was not enough to pull me through the slowwwwwww narrative with seemingly useless details. This one just wasn't for me, but I feel as if I'm in a bit of the minority.

Thank you so much to NetGalle, Orbit Books, and Sylvie Cathrall for allowing me the opportunity to read this book in exchange for an honest review!

My goal this year is to DNF more often, so if this wasn’t an ARC, I would have abandoned this very early on, because I had forgotten that I’m not a big fan of epistolary novels. But, I’m glad I kept with it, because around the 50% mark, it felt as if the plot started moving and was much more interesting. There’s a very distinct authorial voice here, which I think readers of nonfiction might enjoy, as it’s quite academic (though I was surprised that each character has this sort of approach to their writing). Less crazy about the idea of ‘mind maladies’ and the factually incorrect way of dealing with obsessions but also I do just get cagey about that sometimes because I’m sensitive. A difficult read for people like me who prefer gorgeous prose and either things to be happening or a character study, but I think for people who are more visual readers this would be excellent. There’s definitely a lush world that’s explored in detail, and while this wasn’t for me, I can absolutely see these things working for a different reader!
⭐️⭐️⭐️ (3.5)
#fantasybooks #fantasea #debut #debutnovel #bookishlove #bookreview #bookthoughts #readingmytbr

Thank you to NetGalley and Orbit books for providing me with a free digital ARC in exchange for an honest review!

This epistolary style book is a little hard to review.
I love the idea of two marine biologists connecting through work that eventually turn to an intimate connection. Placing it underwater makes for an extraordinary setting. As it is so isolating at times you really get a rather raw and vulnerable look at our characters. The actual narrative itself is where I am torn. This is a very slow building story. I think this works better as a long term read. Great for those longer nights in the fall and winter where you can tuck into a few notes with a cup of something warm.
Its also written in a more classic style. There's a lot of nuance here and if you just read it over a short term I feel like a majority of it is going to feel like useless context to a lot of people.

A cozy mystery to read when you are longing for the sea. Slightly slow in pace, a gamble for mood reads, and an unassuming sweet story of connecting through loss. The last third had me flying through the pages, can’t wait for the next book.

4.5 stars

Thank you to NetGalley and Orbit Books for providing me with an eARC of this book in exchange for an honest review!

I was honestly enchanted by this book! "A Letter to the Luminous Deep" is author Sylvie Cathrall's debut novel--an epistolary romantic fantasy set in a unique world under the sea.

Long ago, in an event only referred to as "The Dive", the world in the sky collapsed, leaving its survivors to create their own existence within the ocean. Presently, this world's occupants live either just on the surface or underseas. Our story focuses on E. Cidnosin, who lives in a unique dwelling called the "Deep House", created by her late mother that is entirely submerged underwater. She discovers an unknown marine species outside her window and writes to the renowned Scholar Henery Clel for advice on this discovery.

E. and Henery strike up a penpal-esque correspondence, which blooms into a beautiful friendship and romance. Through their correspondence, they uncover mysteries and secrets unbeknownst to nearly all in their underwater world. As they continue their investigation, a seaquake destroys the Deep House and leaves E. and Henery missing, presumably dead.

One year later, E.'s sister Sophy and Henery's brother Vyerin resolve to uncover the mystery of their siblings' disappearances. The story is told through letters, journal entries, scholarly reports, etc. Letters from E., Henery, Sophy, Vyerin, and other charming characters feature to tell the story. Sophy and Vyerin begin to unravel the mystery behind E. and Henery's disappearance and learn more than they could have imagined about their world and their siblings.

I'll leave it there so as to not spoil the plot! This book had me intrigued the entire time and constantly wondering about the mystery of E. and Henery's disappearance. The epistolary format did take some time to get used to, but it was such a unique way of storytelling that captured my heart! I was fascinated by the world Cathrall creates in this book--an underwater civilization created after "The Dive". The story slowly reveals details of the world as you read--the three academic campuses (Boundless, Atoll, and Intertidal) and the scholarly schools within. We learn of E.'s late mother's architectural prowess that led to the Deep House--the first dwelling of its kind. The occupants of this world cannot breathe underwater, so they don diving suits and utilize depth-crafts to navigate the seas.

While I overall thoroughly enjoyed this story (more about that soon), there were a few aspects I didn't entirely love. For one, the story is told through letters from several characters, but none have their own voice. It became difficult to discern who was "speaking" due to the same voice being used. The writing was also very formal (a little stilted) and didn't have much personality to it. I found it difficult to read at times because of its verbiage. Secondly, I found the world building to be very lacking. Even after finishing, I don't have a great grasp on the world and how it operates. We learn a lot through letters written by people who know everything about this world, so most aspects are not explained. Don't get me wrong, I love figuring it out myself, but I wish we had a more detailed history, because I was *so* fascinated by this world!

Now, for what I liked (which is most of it)! Firstly, our main character E. suffers from OCD and severe anxiety--I thought it was an accurate representation and enjoyed having a character like her! Her two siblings, Sophy and Arvist, are much more extroverted than E. and both conduct lives outside of the Deep House. Sophy was an incredible character as well! Her sisterly love for E. shines through her letters, and we get to read about how she met, and subsequently fell in love with, her wife on an expedition! The world created in this book is so unique and mesmerizing! I loved reading about the different academic campuses, what types of research they do underwater, and how life has adapted for humans living within the seas. The plot gripped me from the very beginning and didn't let go until the last words (I am eagerly awaiting the next book)! I also adored the relationships between the characters and seeing them develop throughout the book. This was overall such an enjoyable read and I cannot wait for the next book in the Sunken Archives series!

Let me start off by saying that this book has been compared to Heather Fawcett’s Emily Wilde series, just in an underwater world, so that comparison set my expectations very high.

I like an epistolary novel as much as the next person, but when it’s the entire novel, and all of this correspondence sounds like it’s in the same voice, the narrative starts to feel monotonous and sluggish, no matter how pretty the words are.

The underwater world concept was interesting and I was intrigued by the mystery of what caused the death of two of the main characters. These elements were really the only things propelling me through and unfortunately they just weren’t quite enough for me.

Thank you to NetGalley and Orbit for providing this ARC in exchange for my honest review!