The Devil’s Mouth (2026) Review – A Killer Shark With No Teeth

Welcome to Knockout Horror and to our review of Amazon Prime Video exclusive shark horror The Devil’s Mouth (2026). I was pretty hyped for this release so it pains me to say that you definitely don’t want to be renewing your Prime subscription just to watch. This is about as average as they come. Let’s take a look.

Another Shark Movie Set in Thailand?

Honestly, I am starting to feel a little sorry for the shark population of Thailand. Those guys need to get a new agent or some better PR.

“If you are off to Thailand, don’t be afraid to dip your toes into the water and enjoy the glorious scenery.”

We started off this week with Thai tiger sharks chomping people’s legs in The Bay (it was bad, still read the review, though). Today it’s a marauding Bull Shark haunting a Thai cave system in The Devil’s Mouth. What makes it even more baffling is that Thailand has a massive tourism industry and there have only been a tiny handful of non-fatal shark attacks over decades and decades.

Now, for all you aspiring visitors to Thailand, I am here to put your mind at ease. The country doesn’t have an enormous problem with sharks, it just offers extremely lucrative cash-rebates to foreign filmmakers.

Production companies are afforded generous incentives purely for spending money in the country and further bonuses for promoting Thai tourism, hiring local Thai crew, shooting in specific tourist locations, and handling post production locally.

So there you go. If you are off to Thailand, don’t be afraid to dip your toes into the water and enjoy the glorious scenery. Back on with the review; The Devil’s Mouth is a very standard shark horror movie plot with a tiny difference – it’s set in a freshwater cave system.

The same old shark movie but slightly different

A group of friends on a vacation to Thailand decide to head into a cave system that was once beloved by one of their fathers. What starts as an ordinary adventure featuring swimming and spelunking, quickly turns into a nightmare as the group are hunted by a freshwater predator.

The shark movie formula is so done to death that it is very clear that filmmakers are struggling to find new ways to put a twist on it. Putting pen to paper, the most obvious setup for any writer is likely to start with “a group of friends on vacation”.

It’s no surprise that the slight spin placed on the formula by writers Aja Gabel and Myung Joh Wesner afforded it the opportunity to be picked up by a major production team like Amazon MGM.

Shark movies sell well with action hungry audiences and the glorious locations populated by scantily dressed characters only add to the appeal. This movie features at least one pretty big star, too.

Kathryn Newton is a scream queen who is just coming off a hot streak. She experienced tremendous success with a major role in Ready or Not 2: Here I Come after starting out her career as a young teen in Paranormal Activity 4. She’s also had major roles in movies like Lisa Frankenstein and Abigail and is a genuinely great actress.

The rest of the cast is slightly lesser known but both Lana Condor and Tommi Rose have tons of experience. Sure, you would be well within your rights to wonder why this collection of college students is played by a bunch of actors kicking 30s’ door down, but that’s horror for you.

The Devil’s Mouth has everything it needs to work. A decent premise, a star actor, a competent cast, a stunning location, and a decent budget.

So what went wrong?

Believe it, or not, the question of what went wrong here is quite difficult to answer. Fundamentally, the vast majority of The Devil’s Mouth is just average. Director Jeff Wadlow knows his way around the director’s chair, having brought us the pretty decent Kick Ass 2 back in 2013. His latter career has been marked by horror mediocrity, though.

“This is an unlikable group with only one character to root for, Sara, and one particularly horrible character in the aforementioned Max.”

Titles like 2020’s Fantasy Island, 2022’s The Curse of Bridge Hollow, and 2024’s Imaginary showed that Wadlow could be consistently given big names, great locations, and a decent budget yet still produce middling horror that struggled to reach a 5.0/10 IMDb user score.

The best word I can use to describe The Devil’s Mouth is “dull”. It’s a dull film that will have you spending more time watching people clinging to rocks than actually fighting for their lives. The problems start almost immediately. This is a classic case of needless padding.

Kathryn Newton’s Sara and Lana Condor’s Max have a very toxic friendship and that’s going to play a pivotal part in the story… Only, it isn’t. I won’t go into it for spoiler’s sake but, suffice to say, the back and forth between the two characters takes up a ton of screen time and for little payoff.

Every other character is just window dressing. You have the angry guy who shouts a lot, the dude with a six pack and the mental age of 12, the boring tour guide, and the busty girl who spends most of her onscreen time flashing her butt at the camera.

This is an unlikable group with only one character to root for, Sara, and one particularly horrible character in the aforementioned Max. Their interactions are going to get old, fast.

The action is incredibly tame and middling

The Devil’s Mouth is rated PG-13 and it’s very clear that this rating becomes a massive ball and chain when it comes to violence. It’s noticeable in a pointless skinny dipping scene that clumsily goes out of its way to avoid showing an arse or a nipple but even more of an issue when the shark attacks start.

There are kills but, for the most part, they are heavily obscured and not at all exciting or gruesome. This is a huge problem because shark movies live or die on their brutality and special effects. You’ll be begging to see something suitably gory but it won’t ever come.

Speaking of special effects, the shark doesn’t look terrible. It’s CGI but it isn’t the type of CGI you would see in an Asylum produced shark movie so it’s tolerable. I can’t say the same about the jellyfish horde earlier in the film, though, which look absolutely awful.

The small cast means it takes an age to get to the first kill and the subsequent kills are few and far between. This movie has a 100 minute runtime with about 10 total minutes of shark themed action so you can imagine what the rest is. Characters arguing, characters clinging to slippery rocks, and characters looking for air pockets in caves.

“You’ll be begging to see something suitably gory but it won’t ever come.”

It’s very dull and extremely slow. There’s so much meandering that I wouldn’t blame you for one second for reaching for your phone and doing a little scrolling to pass the time. A lot of these issues are compounded by an extremely dark, eye straining picture and a script that goes way beyond laughable, in parts.

On the plus side

There are a few positives. Some of the scenery shots are gorgeous and the underwater photography can be pretty fantastic in the caves. I have to commend the cast, as well, for how well they did with some of the more action based scenes.

Everyone obviously showed up ready to put in work and it’s impressive to see them engaging physically with many of the stunts. There is one underwater chase through the cave system that was actually pretty neat so kudos for that.

Kathryn Newton is fantastic. She somehow manages to push aside the clumsy script and lousy character writing to create a nuanced protagonist that you want to root for. Lana Condor is incredibly obnoxious, as Max, but I think that was her instruction so she did a great job with that.

All in all, The Devil’s Mouth is a tiny cut above your bottom-rung shark movie but that’s not really saying much. It’s too slow, too dull, and far too tame to really recommend. If you have high tolerance for meandering, slow-paced shark horror, maybe give it a go.

Our Scoring Philosophy: A Fair Fight

Horror is a genre that thrives thanks to indie film makers and low budget creators. At Knockout Horror, we firmly believe that every movie that we review deserves a fair fight. That's why we grade on a curve. Our star ratings are all about context, judging a film on what it achieves with the resources it has.

A 4-star rating for a scrappy indie horror made for $10,000 is a testament to its ingenuity and raw power. A 4-star rating for a $100 million blockbuster means it delivered on its epic promises. We don't compare them side-by-side; we celebrate success in every weight class, from the back-alley brawler to the heavyweight champion. Please keep this in mind when considering star ratings.