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A Wall Street Journal
Searching for a missing diver takes a Florida detective on a deep-diving adventure in a gripping thriller by the Amazon Charts bestselling author of .


After the Underwater Investigation Unit’s disbandment, public outcry ushers Sloan McPherson and her partner, former navy diver Scott Hughes, back into the depths of crime solving. But Sloan’s return comes with a personal case.

Longtime family friend Fred Stafford has disappeared. Left behind: his abandoned truck in the vicinity of an unmarked sinkhole and new findings that have Sloan second-guessing everything she thought she knew about the man. There are his gambling debts, his association with a treasure-hunting band of underwater cavern junkies called the Dive Rats, and most alarming of all, a discovery in Stafford’s storage shed that raises the stakes even higher and plunges Sloan into an unfathomable mystery.

As Sloan’s investigation unfolds, a tragic Florida cold case, local superstitions, and a shocking conspiracy collide. For Sloan, finding Stafford and uncovering the buried secrets of the past soon drag her deeper into the dark unknown than she feared.

296 pages, Kindle Edition

First published March 12, 2024

1331 people are currently reading
4963 people want to read

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Andrew Mayne

69 books2,944 followers

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Displaying 1 - 30 of 367 reviews
Profile Image for carol. .
1,760 reviews10k followers
March 7, 2024
I have a theory (of course I do). By book five in a mystery series, we know it is going to be, well, A Series, meaning the author has developed a brand, certain genre conventions will be adhered to and, most importantly, the author has practiced enough to be decent at what they are doing. But here’s the hypothesis part: the author finally has enough publishing security to start to challenge themselves and the readers to break from earlier patterns. I present as evidence Matthew Scudder book 5 and 6, (Eight Million Ways to Die and When the Sacred Ginmill Closes), two of my favorites; Elvis Cole 4 and 6 (Free Fall and Sunset Express); Charlie Parker 4 and 6 (The White Road and The Unquiet). Possibly I could go on, but this is about Mayne and how Dark Dive, book five in Payne’s Underwater Investigation series, dares to diverge from its predecessors and becomes an even more interesting book.

The series is about a statewide Underwater Investigations Unit which ostensibly is brought in when there are cases that involve diving, particularly evidence retrieval. It is a small unit, comprised of a charismatic, politically-savy head, George; our narrator and archeologist in-training, Sloan; ex-Navy diver and tech-geek, Hughes, introduced in book 2; and the more recent ex-PD detective and data miner, Gwen, from book 4. (If you are getting the feeling you should read the series in order, that is quite possibly true. It depends on your tolerance for continuity). Prior to this, the Unit had seen some rocky political ground and temporary disbandment, but all is copacetic now. As a reader, I found this a huge relief; while intrusive agency politics may be a draw for some, I find them about as fun as kingdom politics in fantasy series, which is to say, hardly at all. It is enjoyable to witness the team each perform their roles in competent ways and try to solve the puzzles they are presented with.

And what a puzzle! A dive shop owner is concerned a well-known but eccentric diver has gone missing; the soon-to-be ex-girlfriend had filed a missing persons report but his new diving buddies are clueless and strangely unconcerned. As Sloan starts asking questions, she discovers she hardly knew the man. The case gets more complex in diverging but extremely interesting ways and I was on board for it, if a little confused once or twice. But here’s the thing–I want to re-read it because of it. It is one of those mysteries where the complexity invites one to think and reconsider, much like re-watching a magic trick. “Wait, show me again,” is, in my estimation, a good response to have in both scenarios.

Writing continues to improve. Sloan’s main focus in the case and she doesn’t spend a ton of time in the emotional back-and-forth of family dynamics, one of the areas where I have historically felt characterization was more weak. The endless glades of southern Florida really come alive, as do the deep sinkholes, and I felt myself in that muggy, grassy plain listening to insects buzz. Yep, definitely want to re-read it again (but honestly, not revisit the Glades again). There are a few spots where I felt a careful editor might have improved sentence flow or word choice, but on the whole, I'm going to say it's above competent.

My deepest hesitation is the ending, which felt a little like it jumped the shark. Well, whatever; got to give the genre what it expects, I suppose, but that was what left me with the most questions the next day. Aside from that, it would have been an easy five stars for an engaging story and puzzling mysteries. I definitely recommend it.

many thanks to Netgalley for the advanced e-copy for review. all opinions are you know, like, my own, man
Profile Image for LIsa Noell "Rocking the chutzpah!".
737 reviews577 followers
March 18, 2024
My thanks to Thomas and Mercer, Andrew Mayne and Netgalley.
You know..after the last book I was really freaking worried that I may have to give up this series and probably send a bunch of dead alligator heads to the author. Yes, I had, "had being the operative word" a brother in law who thought it was hysterical sending me alligator heads. "3 of them!" What a fool. My neighbor's son loved them.
However...I just loved this book! My favorite thing? Yes, it was the end! Not because I was tired of it, but now I know that the U.I.U. is now going bi-coastal! Thank goodness! I'm about tired of the gators. I love this series, and I'm happy it's finally going back into the water. That's why I signed up for this series!
Profile Image for PamG.
1,312 reviews1,051 followers
March 9, 2024
Andrew Mayne brings action, suspense, and mystery to Dark Dive , the fifth novel in the Underwater Investigation Unit series. Add to this, underwater caverns, archaeology, and a missing family friend and readers are in for another exciting adventure with Sloan McPherson and Scott Hughes.

The Underwater Investigation Unit is back in business. Besides Sloan and Scott as well as their leader Geoge Solar, they are now joined by Gwen Wylder, a contractor to help research cases. Readers of the series met Gwen in book four. The story kicks off with a longtime family friend of the McPhersons disappearing. As they search for him, several alarming items become known. The situation is not nearly as straightforward as one might initially think.

Sloan has good reflexes, amazing instincts, and doesn’t shirk responsibility. She also has a discerning sense of justice and determination that makes it easy for readers to get behind. However, she takes risks and has trouble with people who ignore clues and go for the quick resolution. Hughes also has a somewhat reckless streak, but has incredible analysis capabilities as well as some skills from his military career. He’s also the technical equipment and robotics member of the team. Both have a police background which helps since the UIU is a law enforcement agency. Together, they are a formidable pair of investigators. Gwen can be abrasive and rude, but she’s also extremely smart and analytical.

The plot is multi-layered and has twists and turns to keep a reader guessing. The world-building is excellent and I was easily transported to Florida. The well-written story and the incredible characters combine with action and multiple mysteries to culminate in an action-filled conclusion. Mayne is an exceptional storyteller who provides readers with gripping scenes that move at a blistering pace. The final chapter provides the thread for the next book in the series and hints at changes that are coming. How will the team adapt? Themes include deaths, disappearances, political pressure, family, friendship, greed, and much more.

Overall, this was an intense story with complex characters that kept me turning the pages. I was surprised several times by events. This kept the tension level high throughout the book. Those who enjoy crime thrillers, mysteries, and police procedurals may want to check out this series.

Thomas & Mercer and Andrew Mayne provided a digital ARC of this novel via NetGalley. This is my honest review. All thoughts and opinions expressed in this review are my own. Publication date is currently expected to be March 12, 2024.
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My 4.23 rounded to 4 stars review is coming soon.
Profile Image for Liz.
2,843 reviews3,759 followers
February 3, 2024
I’ve been a fan of the Underwater Investigative Unit series, but this one didn’t work quite as well for me. The Unit has been re-assembled, and Gwen is now working for them. I enjoy the team and their interaction.
This time, it’s an old family friend of Sloane’s who has gone missing. He’s also an expert diver. But he seems to have had quite a few secrets in his past. And when they find a prehistoric mummified body in his storage unit, well, let’s just say it really strained credibility. Although I’ll give Mayne credit for sneaking in some facts about the ancient history of the region.
There was one point in the book when I felt like one of the side plots was borrowed a little too heavily from another recent book. And it didn’t really add to the main storyline.
This is a good series for folks that like entertaining thrillers and aren’t concerned with believability. It’s a thrill a minute with very little downtime. Sloane isn’t known for walking away from risky endeavors. But things are catching up with her and she’s beginning to think about a life beyond always jumping into the unknown.
This could work as a stand-alone.
My thanks to Netgalley and Thomas & Mercer for an advance copy of this book.
Profile Image for Debbie.
500 reviews77 followers
March 12, 2024
Happy Publication Day! March 12,2024!

Andrew Mayne's Underwater Investigation Unit (UIU) series has always been a favorite of mine. This is the fifth book in the series and as with all the other books it has good pacing and a lot of suspense and intrigue.

The last book had grounded the UIU team and kept the strong female protagonist, Sloan McPherson, and her cohorts mostly out of the water. This time, they are all back together again and diving into deep waters with alligators and crocodiles as they are looking for an old friend who is an experienced diver and has gone missing. The team uses all their investigative skills in and out of the water to find him, including a small, talking, robotic dive machine. Their methodical search leads them to new clues, new suspects, and danger around every corner. There is even a hint about what new adventures may await the UIU in the future.

I'm always on the lookout for new books by this author. I highly recommend this book to readers who love fictional action adventures and suspenseful investigative mysteries. It's never too late to "dive" into this series.

Many thanks to Thomas & Mercer and NetGalley for giving me the opportunity to read a digital ARC of this book. All opinions expressed are my own.
Profile Image for Valleri.
1,017 reviews45 followers
April 9, 2024
After the Underwater Investigation Unit’s disbandment, public outcry ushered Sloan McPherson and her partner, former navy diver Scott Hughes, back into the depths of crime solving.

Back into the depths is right! Longtime family friend Fred Stafford has disappeared. He's left his truck, gambling debts, his association with a treasure-hunting band of underwater cavern junkies called the Dive Rats, and an astonishing discovery in his storage shed.

I found Dark Dive to be utterly fascinating. I learned so much about AI! I also loved the wee glimpse of Theo Cray. I hope this series NEVER ends!

#ThomasAndMercer #AndrewMayne #NetGalley #ScubaDiving
Profile Image for Lorelei.
366 reviews43 followers
February 6, 2025
Thanks to @netgalley for the advanced copy of this book!

My rating: ⭐⭐⭐

Dark Dive is the fifth book in the Underwater Investigation Unit series. Florida detective Sloan McPherson has been diving all her life, and now she uses those skills to solve murders, stop corruption, and help as many people as she can. But you can hide a lot of secrets in the dark waters of Florida, and this time it seems a missing friend was keeping secrets of his own. Sloan and her colleagues have to race to solve the disappearance before those secrets cause even more harm.

On a technical aspect I was a bit frustrated when the character talks about taking oxygen tanks to depth as a backup - any diver knows that pure oxygen, when breathed below about 18 feet, will cause convulsions and drowning. Presumably the author meant oxygen enriched gases, but a non-diving reader wouldn't know that. You could argue it's not necessary to explain this for the story, but misinformation that can lead to death seems unnecessary - why not just say 'tanks'? Also, there's a story line regarding a school and identity that are entirely unresolved. There's no mention at all at the end, so it's unclear if the author intends to delve further into it in the next book, or that plot line was just dropped, but it left me unsatisfied.

I did love the line where the main character mentions that she's way more worried about a boat driver ignoring a dive flag in the water than a shark... Amen to that. Those boaters are a menace.

All in all, it was an enjoyable thriller with some clunky parts.

Dark Dive will be released on March 12, 2024!
Profile Image for Matt.
4,858 reviews13.1k followers
February 11, 2024
First and foremost, a large thank you to NetGalley, Andrew Mayne, and Thomas & Mercer for providing me with a copy of this publication, which allows me to provide you with an unbiased review.

Eager to get my hands on Andrew Mayne’s latest novel, I devoured this recent quasi-police procedural. I discovered Mayne through the debut novel of this series and have been enjoying much of his work since. Taking a unique spin on police work, Mayne sheds some light on a great means of discovering crimes and catching those who commit them. With a great deal of attention to detail, Mayne is able to check all the boxes and keep the reader engaged until the final page.

With the dissolution of the Underwater Investigation Unit (UIU), there is significant blowback. The uproar eventually sends Sloan McPherson and her partner, Scott Hughes, back underwater to solve crimes and plunge to new depths while doing so. However, things are slow to get started, giving Sloan some time to play hero, as well as victim, during some dives across Florida.

Sloan finds herself in the middle of a personal case as the UIU returns to business. Family friend and famed diver, Fred Stafford, has disappeared without a trace. Working with Scott and using her intuition, Sloan is able to locate Fred's truck, which has been left abandoned near a sinkhole. Fred, always the adventurous diver, has used his skills to explore many uncharted spots, of which this might be one. While Sloan prepares to explore the area, she stumbles across some news that tosses her for a loop and leaves her wondering if she ever knew Fred Stafford at all. A group of underwater diving enthusiasts who seek treasure have been scavenging with Fred whenever possible. Their finds are surely being sold on the black-market, which would cover Fred's large debts accrued from a gambling addiction. If that were not enough, a discovery on Fred's property opens up new and troubling revelations.

As Sloan and Scott keep working the case, they call in outside assistance to locate Fred Stafford. Things morph into a cold case with significantly problematic evidence that leads Sloan to wonder what is actually going on. With the UIU back in play, Sloan will have to represent them as best she can, knowing that each dive and every question could take things in a horrible direction with little knowledge of what waits under the murky waters. Mayne does a fabulous job at pulling the reader into the middle of the story without letting go.

I have long enjoyed the stories that Andrew Mayne writes. As I mentioned above, this was the first of his series that I discovered, though I have never found a book of his that I disliked. Filled with great narrative flow and action, Mayne keeps things moving and never lets up. There is something about the unique perspective that has long interested me. Sloan McPherson does well to provide the reader with the insight needed to respect diving and how it fits into policing. Peppering in great ideas and developing them throughout, Mayne proves his worth and keeps the reader fully engaged as the mystery thickens throughout the novel.

Plot points grow as the story builds, thrusting Sloan McPherson into areas of the law and her personal life she had not expected. As Mayne explores the world of diving and the risks undertaken by those who thrive on adventure, the story follows along and keeps things on edge throughout. Mayne knows how to use the proper pacing and keeps the reader involved in the many twists he inserts throughout the story, always willing to surprise when things seem to be on the straight and narrow. I am eager to see where things will go with this series and if there will be more than a passing 'crossover moment', as Mayne brought in one of his other great protagonists to offer up some of their insight.

Kudos, Mr. Mayne, for another thrilling novel that has me eager for the next instalment.

Love/hate the review? An ever-growing collection of others appears at:
http://pecheyponderings.wordpress.com/

Be sure to check for my review, first posted on Mystery and Suspense, as well as a number of other insightful comments by other reviewers.
https://www.mysteryandsuspense.com/da...
Profile Image for Megan.
251 reviews25 followers
December 25, 2023
4.5/5

This is definitely one of my favorites in the series.
Sloan McPherson and Scott Hughes are at it again. The story has everything in it from artifacts from old Florida being found to murder. The book is fast paced and I didn’t want to put it down.

Definitely one of my favorite series to read!
Profile Image for Tracie Gutknecht.
1,208 reviews13 followers
October 24, 2023
Mystery/Thriller

Another adrenaline spiking, heart-pounding, intelligent thriller from Andrew Mayne!

I love this series! The main cast of characters - Sloan, Scott, George and now Gwen are a match made in fiction heaven.

The novel begins with Sloan getting called to help retrieve bodies from a van that has crashed in the water. These are bodies that were on the way to the lab for forensic testing in a serial killer case. The problem with this particular body of water is that there are a number of alligators in this pond and its mating season. The story explodes from there.

Sloan's next task is to look into a missing person. He is a family friend and fellow diver, and no one has seen or heard from him in about a week. While investigating, Sloan turns up all kinds of irreconcilable data and makes a few discoveries. I won't spoil it here, but one of the discoveries creates a very interesting backstory for the missing diver.

The investigation causes Sloan to investigate some remote parts of central Florida. The author then gets to reveal some interesting facts and history about the state and the creation of underwater caves. Mayne also gets to geek out on some new robotic technology that gets used in the case.

It was a stellar novel - so, why only 4*? I have to say that I was disappointed with the ending a bit. It's still great, but the author didn't do anything with the side story about the missing diver's background. This background story plays a huge role, and it feels unfinished. I, also, think that the "whodunnit" and the ensuing finale went very quickly and so it also felt incomplete. I'm still a huge fan of this series and Andrew Mayne and will continue to read everything he writes. His novels are just so smart!

Thank you to NetGalley and the publisher for my ARC of this novel.
Profile Image for Ashley Duckham.
37 reviews20 followers
August 11, 2024
Fantastic read! One of my favorite in the series. Mayne is great at setting the atmosphere and pulling you in right there with them. Book 5 was focused more on the underwater aspect which was refreshing as I think that’s why we all gravitate to this series. Overall, 5 stars. Cant wait to see where he takes us next!
Profile Image for Amrita Goswami.
346 reviews38 followers
April 10, 2024
This was the perfect flu read. There's nothing like sniffling in bed wrapped in a cocoon of blankets and reading about badass cops who dive into alligator and crocodile infested waters.
Also, characters say things like "when we hang up our fins.." with a straight face. Good fun.
Profile Image for Samantha.
422 reviews43 followers
March 11, 2024
After a brief hiatus the dream team Sloan+Solar+Hughes are back & dive deep into a brand new gripping twisted plot! The prologue reels you in & the plot is one compelling chapter after another but the epilogue ties it all neatly in a bow & may leave you with major withdrawal symptoms for the next book in the addictive UIU series. With the mix of an unusual unique plot with quirky characters this book is one I found very difficult to put down.
The only disappointment comes from the fact that I read this book before Sea Castle & never wrote down a review for this one despite having feasted(figuratively)on this book. So now I no longer have a UIU book on my shelf & desperately seek the next thrilling adventure Sloan gets to go on. #stupidme

Thank you NetGalley, Thomas and Mercer, Andrew Mayne for the arc!
Profile Image for Valerie.
736 reviews14 followers
February 4, 2024
I highly recommend, I enjoyed this very much. I was a bit puzzled by how it starts out but it is all explained later in the story. I don’t know much about diving and can’t imagine the scenarios they have to go through but the ones described here are pretty intense. I would have liked to know who Fred really is but alas it didn’t reveal that. The story makes it plain that there is a group of people who are the only suspects but it is impossible to tell who the killer is till the very end. The book has lots of tension and action, but it be Nile crocodile never shows up. #DarkDive #NetGalley
Profile Image for LianaReads blog.
2,802 reviews249 followers
December 15, 2023
Having devoured the first four books in the series, the return of Sloan McPherson in "Dark Dive" by Andrew Mayne had me eagerly diving back into the underwater investigative world. The book maintains the series' stellar pacing, an engaging plot, and believable twists that set it apart from typical crime procedurals. Sloan remains a remarkably well-developed female lead, anchoring the narrative with her depth and complexity. While the plot marks an improvement from the fourth installment, my only qualm was the somewhat abrupt introduction of AI elements. The frequent, almost infomercial-like mentions felt a touch forced. Despite this, the concept added intriguing layers to the story, enhancing its authenticity. "Dark Dive" weaves a gripping tale of mystery, unearthing buried secrets, and navigating the depths of a Florida cold case. Mayne's expertise shines through, making it a thrilling addition to the Underwater Investigation Unit series.

Very grateful to the publisher for my review copy through NetGalley, opinions are my own.
Profile Image for William de_Rham.
Author 0 books84 followers
December 15, 2023
This is a good mystery/thriller about underwater investigations by specially trained Scuba divers. Set in Florida in and around, not the Atlantic or the Gulf, but various sinkholes—some of them ancient—located within the state’s interior, it contains lots of very good research and information about a variety of subjects, including but not limited to alligators, crocodiles, anacondas, pythons, professional and amateur diving, Florida’s ancient history and geology, as well as sinkholes and what they can contain.. The characters are interesting. The settings are well described. While it’s a “who done it,” I didn’t find the central mystery to be all that compelling. especially since we never really get to meet, and thus become involved with, the victim. But author Andrew Mayne created some very tense scenes, especially underwater, that kept me on the edge of my seat. 3.5 stars rounded up to 4.

My thanks to NetGalley, author Andrew Mayne, and publisher Thomas and Mercer for providing me with a complimentary ARC. The foregoing is my independent opinion.
Profile Image for Paula.
1,322 reviews48 followers
October 21, 2023
Dark Dive by Andrew Mayne is atmospheric and a bit creepy. Searching for a missing diver takes a Florida detective on a deep-diving adventure. The book is part of a series, but this story can be read as a standalone book.

I liked the characters and felt they were well-developed and three-dimensional. Their actions were realistic and appropriate. Sloan is a great character, and her family is fun to read about.

I may go back and read the previous books in this series. I will read more by this author and in this series. The story was intriguing, the characters were likable, and the writing was engaging.

#DarkDiveAThriller #NetGalley @AmazonPub
Profile Image for Eileen Goudge.
Author 120 books711 followers
March 18, 2024
Page-turner

This is the latest book in the series that I’ve read. I’m hooked. I’ve always been intrigued by deep sea diving, and this series takes it to places I never dreamed of, such alligator-infested waters, with crime solving to heighten the drama. In this book, Sloane and her underwater investigative team are searching for man known to Sloane who disappeared under suspicious circumstances. It’s full of twists and turns, including the discovery of a 15,000 year old mummy, and kept me guessing.
Profile Image for J Kromrie.
2,525 reviews47 followers
February 12, 2024
Thanks to Netgalley and the publisher for this eARC.

Andrew Mayne's latest thriller, "Dark Dive," plunges readers into the murky depths of suspense and intrigue. Set against the backdrop of Florida's sun-soaked coastline, this gripping novel takes us on an underwater adventure that will leave you breathless.

Detective Sloan McPherson is no stranger to the mysteries of the deep. After the disbandment of the Underwater Investigation Unit, she thought her days of diving into treacherous waters were over. But when a family friend, Fred Stafford, vanishes without a trace, Sloan is pulled back into the abyss.

Mayne's writing is as sharp as a harpoon, propelling us through a labyrinth of secrets and submerged danger. The short, punchy chapters keep the pace relentless, mirroring the urgency of a diver running out of air. Sloan's first-person narration adds an intimate layer, allowing us to feel the pressure of each descent and the weight of every revelation.

Stafford's disappearance leads Sloan to a tangled web of clues: an abandoned truck near an unmarked sinkhole, a gambling debt, and an enigmatic group of underwater treasure hunters known as the Dive Rats. As she dives deeper, she unearths a shocking conspiracy—one that threatens to drown her in darkness.

The Florida setting comes alive under Mayne's skilled pen. The salt tang of the ocean, the oppressive humidity, and the eerie beauty of submerged caves—all are vividly rendered. And just when you think you've caught your breath, the author twists the plot, revealing layers of deception that ripple through the narrative like a riptide.

"Dark Dive" isn't just a thriller; it's a love letter to the ocean. Mayne's meticulous research shines through, making diving feel both exhilarating and perilous. Whether you're a seasoned diver or a landlubber, you'll find yourself holding your breath as Sloan navigates treacherous currents and uncharted depths.

In Sloan McPherson, Mayne has crafted a resilient and complex protagonist. Her determination to unravel Stafford's secrets drives the story, but it's her vulnerability—the fear of losing someone she cares about—that resonates. And let's not forget her partner, former navy diver Scott Hughes, whose unwavering loyalty adds depth to their dynamic.

"Dark Dive" is a pulse-pounding thriller that submerges readers in a world of shadows and secrets. Mayne's prose is a tidal force, pulling us into his vortex.
Profile Image for Ray Moon.
347 reviews10 followers
February 23, 2024
Trying To Break Into A Tight Knit Group

In central Florida, 11,867 BCE, Niquia is out near the seashore looking for some snails that her mother told her would with the pregnancy. A stranger comes up behind her and tries to catch her. She runs and is hit by something in her shoulder. She crosses the stream and runs through some mangroves. She finds herself at the edge of the forbidden Darkland. She is hit again in the neck by a small rock. She must escape, so she enters the Darkland. This event, which happened almost 14,000 years ago, leads to the events in this novel.

The one main storyline is the search for a master diver, Fred Stafford, who is a good friend to Sloan McPherson and her father. Fred just disappeared with his van and gear. While it is common for Fred to leave for jobs worldwide, there were no indications he did this time. As the Underwater Investigative Unit is being stood up after a short disbandment, there is free time to look for Fred. As Sloan and Scott Hughes start the investigation into what happened, they discover a darker side and a group of possible suspects. The suspense is maintained by the hope of finding Fred alive. As Sloan and Scott’s investigation continues, several what I call literary grenades significantly change the investigation's complexion. Like most previous novels in this series, the flow of action is fast, with Sloan still taking some risky chances. These situations occur at a lower rate in this novel than in the previous novels. I found the novel easy to follow, which having a single narrator, Sloan, facilitated. My attention was captured quickly and maintained to the end.

With a new character, Fred, who has a long history with Sloan and her father, the background of Sloan's character is expanded with new background information. As mentioned previously, Sloan finds herself in situations where she wants to take more risks but backs off. She is maturing. She even says that she needs to cut back on risk-taking. The new information on Sloan in this novel increased my enjoyment of reading.

Some aspects that can cause some readers to stop reading are low-key in this novel. There are no intimate scenes. Bad and impious language are at a minimum. The only violence is when a giant male alligator takes an interest in Sloan McPherson when she goes swimming in his domain. Lastly, this is the fifth novel in the series, but all references to events in the past novels are generic enough not to require you to have read them to understand their relevance to what is currently happening. Overall, I do not believe that this will be an issue.

There is one major problem I have with this novel. A significant loose end is not explained by the end of the novel. This loose end is a spoiler, so I am not revealing it in my review. When an author leaves such a significant loose end unexplained, it leaves a bad taste in my mouth. Otherwise, this novel has all the aspects I have come to enjoy in this series. The pace is fast but still easy to follow. There is plenty of short-term suspense where disasters during the diving are avoided. Lastly, I did not want to stop reading the novel.

This book is the eighth that I have read, spanning three series. This one novel is not enough to drop this author from my Must-Read category. I already have his next novel in my sights to read and await its availability. This novel has many aspects that I enjoy and for which I read this series and author, but because it has a significant flaw, I rate it as mixed feelings that earn it a rating of three stars. It potentially can be a good read, and it might not.

I received this novel's free prepublication e-book version through NetGalley from Thomas & Mercer. My review is based solely on my own reading experience of this book. Thank you, Thomas & Mercer, for the opportunity to read and review this novel early.
Profile Image for Roxanne Spencer.
393 reviews5 followers
December 10, 2023
As expected, a fun book to read as Sloane and the Underwater Investigations Unit are back in service. First up, Sloane has to jump into a pond full of alligators- a situation that has even her questioning her career choice! Interestingmix of crime solving and archeology that captures Florida perfectly.
Profile Image for Cathy Cole.
2,242 reviews60 followers
March 9, 2024
I always look forward to reading the latest Underwater Investigation Unit thriller. I've learned a lot about diving in different locations-- in Dark Dive, it's sinkholes and underwater caverns-- and about the state of Florida itself. Florida seems to be the home of abandoned "pet/monsters": pythons, anacondas, Nile crocodiles... let alone the native alligators, and Sloan has to take the wildlife into account each time she dives.

The diving sequences are always riveting. You never know what's going to spring at Sloan from out of the murk, and I have to admit that I enjoy the vicarious scares. But it's not all fast-paced thrills and technical gadgetry. I wish every state in the country could have someone with the savvy of Sloan's boss, George Solar. To smooth the way for his investigators, Solar has two RVs-- one filled with lawyers ready, willing, and able to get search warrants and other legal necessities, and the second armed with CSI techs and all the lab equipment they need to avoid the interminable delays of local law enforcement backlogs. Sweet, eh?

Even sweeter is the fact that the cast of characters is just as strong as the story, the thrills, and the technology. I like Sloan's irreverent voice, and her partner Scott is increasingly figuring into the stories. In addition, there's always a one-time character whom you wish could become a recurring one. In Dark Dive, it's octogenarian Gayle Pinnesky. I just loved her to bits!

Exciting story, lots to learn, fantastic setting with a touch of the alien about it, and great characters. If you haven't already gone diving with Andrew Mayne's Underwater Investigation Unit, it's time you did!

(Review copy courtesy of the publisher and Net Galley)
Profile Image for Sibil.
1,748 reviews77 followers
April 12, 2024
Thanks to NetGalley and to the Editor. I received a copy of this book in exchange for an honest review

This is the fifth book in this series, and I have yet to read the first four books in it. I know this sounds strange. And when I requested it I knew it was the fifth, I wasn’t mistaken or confused. I have no excuses, but in my defense, I can say that I have the other books on my shelves and that I love this author, and since I have no willpower when we are talking about books… well, you can guess how it went. And it does not help that lately, I am in dire need of some good thrillers. And Mayne has yet to let me down!
So, I requested the fifth book, I got approved (and they were so quick! Frankly, I thought that I would have had the time to read at least the first book before getting an answer, but I am not complaining!), and I devoured it! Now I know that I will start this series ASAP. (And sure, I haven’t finished the other ones but… who cares?? I’ll go there! Sooner or later…).

This book was so hard to put down! It sucked me in and it didn’t let me go till I reached the end. It was so damn good! And there are a lot of good things, too! It was thrilling, it was captivating, it was fast-paced, it was all I was looking for, and more. It was pure bliss. And it took me some time with my thoughts to see that this book wasn’t as perfect as I thought it was. I mean, I loved the book while I was reading it, and I love the book now, it is just so good! But there is a mystery without a solution here, and it was quite a big one too, but in the heat of the moment, I forgot all about it! It’s just later that, with some space between us, I remembered that there was another mystery and that I wanted the answers to that one, too! And this is why, in the end, my rating is 4 stars and not 5. Because I am so in love with this book that I would have given it 5 stars right away! But since I need those answers, and because it is strange that a thriller full of mystery will leave a (big) one without answers (but maybe we will get the answers in the next book? I can’t say, but gosh, I really hope so!). Anyway, I’ll try to say something more about it, let’s see…

We start with a missing person, he is one of the best divers in the region. He is called upon by the military and the police forces to help, he is well known around, I think he is famous too, and he is a friend of Sloan, our MC. And up to this point, things are quite straightforward. I mean, they start to search for him, and they discover that things aren’t really as clear-cut as they thought in the beginning and that it may be something illegal going on. As I said, it’s pretty standard in the beginning. And yet, the author managed to grip your attention, I was glued to the pages, fascinated by the setting, since diving is pretty interesting, also dangerous, a lot! I won’t dive for the life of me, I am not so adventurous, but it is nice to read about it, and to read about people who know what they are doing! I am always fascinated by competence, and I loved this part. I have to confess that I was pretty happy with the things like they were because it is not only the investigative part that made a good thriller but other elements too, like the pace (it was perfect!), the characters (great!), the setting (quite fascinating), and all of those combine together into the making of something new and unique if you do your job right. And Mayne did his job right.
But for him, it’s also pretty standard to go over the top, so to speak. Its books, at least the ones I read so far (I think this one is the 5th one I read by him) have some extras to them, they are always chocking full of twists, or happenings, or whatever, they all tend to be over the top. And this one does not make an exception.
And so the story starts to get more complicated as things do not add up, and new mysteries are added to the main one.
Honestly, I think that this can make the biggest “make it or break it” for you, if this kind of thing usually doesn’t work for you, you’ll hate Mayne’s books, while if you are okay with that (and maybe with a bit of suspension of disbelief) you will love them! I am not the biggest fan of having too much going on (I just decided to drop two series because the author in the late books was constantly trying to outdo herself, and the books were just too much for my tastes, for example), and I can honestly say that, more often than not, these books are too much. But I love them, and I love them for this part too. I love that you can’t put the book down, I love that there is always something else going on, or something else to dig up (both metaphorically and literally!) and I love the adrenaline.

It was hard to put down, so so hard! And the merit is not only of the writing, which is smooth and direct, or the pace, which is fast and constantly moving forward, but also of the characters. I really loved Sloan and Scott, and I have to mention Solar and Gwen. The first is the best boss ever, especially in thriller books, and Gwen is just amazing. I loved Sloan and Scott’s relationship. They are friends who really know and trust each other, and it is beautifully depicted (also, this is one of the main push to go back and read the previous books, because I am dying to see more of their interaction, I want to see how this beautiful friendship developed!). Also, we have a ton of uber-competent characters. I am not only talking about the MCs, who are indeed competent (and also quite original, their background is always fascinating and pretty unique, with some interesting mix in there. I think that getting to know the MCs is, alone, a great reason to read this author’s books!), but also the other experts that are called on the scene, or the police or whatever, we have a lot of competent and smart people between the pages of his books (because this is, again, a general feature in Mayne’s works), and I always love to see them around.

And last but not least, with this constant mix of fascinating setting, unique and intriguing characters, and over the top plot, we start small, with a sort of pretty classical setting/story and we get to some parts with a really high emotional impact, and I don’t know if I was more taken aback (in the best possible way) by the mystery of it, the twists in the plot, or the emotional punch in the gut, that I didn’t see coming but that it’s there waiting for you. It is a short book, and it is a fast reading but it packs a lot. And I loved every second I spent with it!
Profile Image for SusanTalksBooks.
683 reviews212 followers
March 8, 2024
Thank you NetGalley for another amazing Andrew Mayne UIU book, #5 in the series about diver Sloan McPherson, her investigative colleagues, and her family.

This book's pub date is almost here - March 12, 2024 - and I am so glad to have had a chance to review an ARC from NetGalley. I like procedurals that let us stay with key characters, seeing them develop over time and forming a relationship of sorts with them. Mayne's writing moves the plot along at a good clip: this time it is based on a kind of odd fortune-hunting group, with a little drama to open the novel and give a reason for Sloan's growing hesitation for challenging dives.

This book is great, but at this point, I'm tired of reading about Florida swamps and really want to see the group move into new locales, maybe even globally, to mix it up. I would also love to see Sloan move into a position of leadership responsibility, where she isn't just the adventuresome diver. I hope the publisher takes heed of this because otherwise readers will grow bored with the series despite Mayne's good writing. 4-stars.
Profile Image for Yvonne (It's All About Books).
2,710 reviews318 followers
February 14, 2024

Finished reading: February 10th 2024


"Water was once my escape from the land. But now only the most terrifying things come from it. Water once meant life. Now it brings death."

*** A copy of this book was kindly provided to me by Netgalley and Thomas & Mercer in exchange for an honest review. Thank you! ***

Profile Image for Kate R.
1,181 reviews42 followers
March 20, 2024
I really enjoyed this one. I do have to say I really like the narrator on the audiobook though, so I'd probably recommend that format more. This is the 5th in the Underwater Investigation Unit. It can be read as a standalone though. While they don't give a huge overview of past books, it's been awhile since I've read each book in the series and couldn't exactly remember what happened in previous books and I didn't feel lost or confused. I really like this series. It's so different than other police procedurals you read. There's so much more about diving in all of the books and I have absolutely no interest in diving in the real world but it is rather fascinating subject matter. But, let's talk about this book. This was more personal than previous books with the case she was investigating being someone she actually knows. I think it went at just the right pace for most of the book. The thriller part really increased at the end. My only complaint was how fast everything wrapped up. It felt like we'd barely heard who the killer was and then the book was over. I am curious if the series will continue or if Sloane is getting out of the business after all that talk in the book. Still this is a quick interesting read and I would recommend it.
Profile Image for Maria.
1,217 reviews17 followers
March 22, 2024
I stormed through this book because Andrew Mayne is really, really good at writing action packed stories with sympathetic characters that I simply like - a lot!

The scenery was really interesting in this one. Water-filled caves - and the thought of cave-diving - give me mild anxiety. Like ... It's not just a plain no. It's a: Hell no! 😂
Sooooo, I found it quite interesting to tag along - safely breathing on solid ground, above waters. 😇

I really, really, reeeeally like spending time with Sloan - and Susannah Jones. Great narrator!

I also learned something I'd never heard about before: Yum yum yellow!
Something I now pass around to all my shark interested friends and family members. 😁🦈

Bring on the 6th book and new adventures for Sloan! I will absolutely show up for more books in this series.
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