25 Scariest Sea Monsters You Didn’t Know Exist

Posted by , Updated on May 23, 2024

Are you aware that the ocean’s depths are home to some truly spine-chilling creatures? Fascinatingly, we have more knowledge about the cosmos surrounding us than the oceans on our own planet. Even now, we continue to discover new creatures hidden in these sunless depths. To be frank, some of these beings are rather unsettling. Dive into the 25 Most Terrifying Sea Creatures You Didn’t Know Existed!


Tongue-Eating Louse

Tongue-Eating LouseSource: nationalgeographic.com

We’ll start off with a bang. This terrifying creature enters a fish through its gills, eats its tongue, and then attaches itself to where the fish’s tongue used to be.



chimaeraSource: scientificamerican.com

Also known as a ratfish, spookfish, and ghost sharks, chimaeras are believed to be some of the oldest fish in existence. They live in extremely dark and deep water so running into one of these monsters is sure to give you nightmares. Just look at that face!


Frilled Shark

Frilled sharkSource: nationalgeographic.com

With triple pointed teeth, this deep sea shark could do some damage to anything it catches. Plus, it looks simply terrifying.


Terrible-claw lobster

terrible claw lobsterSource: yahoo.com

Discovered in 2007 off the coast of the Philippines, this lobster was very aptly named. Check out those claws! This dude could cut you up and saw you apart like a piece of cheese.


Water Bear

Water BearSource: scientificamerican.com

While most of the creatures on our list are rather large, these guys are tiny. Like…microscopic! What’s freaky about them is how durable they are…kind of like Twinkies. They can survive in almost any temperature and can survive without water for more than a decade!


Mola Mola

Mola MolaSource: huffingtonpost.com

Also known as the Ocean Sunfish, it sounds nice right? Well, think again because it easily weighs over 2,000 pounds (907 kgs)! And although it won’t attack you (It only tends to eat jellyfish…lots of them!), it can be quite a terrifying sight to see the heaviest bony fish in the ocean coming towards you!


Giant Squid

Giant squidSource: scientificamerican.com

These monsters can grow to 59 feet (18 meters) in length. Just their eyes are as big as beachballs! And yes, their feeding habits are just as terrifying as you would imagine. They grab their prey with their tentacles and then bring it in towards their beak. There it is shredded by their tooth-studded tongue before it reaches the esophagus. It’s basically a meat grinder…


Megamouth Shark

Megamouth sharkSource: huffingtonpost.com

Discovered in 1976, this massive shark has a glowing light in its mouth that it uses to attract plankton. Don’t follow the light!


Gulper Eel

Gulper eelSource: yahoo.com

Given that this saccopharyngiformes lives thousands of meters below the sea, not much is known about it. But what we do know is that it’s huge jaws allow it to swallow prey as large as itself!


Goblin Shark

Goblin sharkSource: nationalgeographic.com

Just one look at these sharks is sure to give most people the shivers. Not only that, but these truly terrifying creatures seemingly detach their entire mouth to catch their prey.



GrenadierSource: scientificamerican.com

Although the Grenadier is strange looking, creep factors don’t always rest with looks. This deep sea fish emits an awful odor due to having high levels of Trimethylamine oxide (which is what typically gives fish their strong smell).


Sarcastic Fringehead

Sarcastic FringeheadSource: scientificamerican.com

Although it poses almost no threat to humans, when it’s agitated, this fish will open its enormous mouth in order to fend off predators. Human or not, one look would send us swimming away as quickly as possible.


Giant Isopod

Giant isopodSource: nationalgeographic.com

Found at depths of nearly 6,561 feet (2,000 meters), these scavengers can grow to more than 10 feet (3 meters) in length. Also, they have been around since before the dinosaurs. Why? They’re survivors. They can go 4 years without any food. So although they won’t eat you, imagine running into this thing in the pitch blackness of the ocean. It’s basically an underwater cockroach that’s bigger than a human! And we’re scared of cockroaches when they’re just a few centimeters…


Fangtooth Fish

Fangtooth fishSource: yahoo.com

These bad boys live over 16,404 feet (5,000 meters) below the waves. At that depth, the pressure would crush a human. If you don’t get crushed by the pressure, prepare to be shredded by some terrifying teeth. In fact, this aptly named undersea monster has the largest teeth relative to its body size of any fish in the ocean!



SnaggletoothSource: scientificamerican.com

This creepy looking fish has hooked teeth that help it snag its prey. Moreover, it lives at incredible depths where the sun doesn’t shine. So if you do end up seeing this scary looking creature, its bioluminescent skin and nightmarish teeth will probably leave you with some horrible memories!


Black Dragonfish

Black DragonfishSource: yahoo.com

With razor sharp teeth, this alien-looking fish lives deep under the ocean and generates its own light.


Giant Spider Crab

Giant spider crabSource: huffingtonpost.com

Sometimes what scares us is sheer size. More than 1,000 feet (300 meters) below the surface, you’ll find the largest crab on Earth. It can grow to nearly 13 feet (4 meters)!


Pacific Viperfish

Pacific viperfishSource: businessinsider.com

Living many kilometers beneath the ocean’s surface, these creatures have teeth so large that they can’t even close their mouths.


Vampire Squid

Vampire SquidSource: yahoo.com

Its name, Vampyroteuthis infernalis, literally translates to “vampire squid from hell.” Why? This undersea squid lives in deep water where sunlight doesn’t penetrate, and if you attack it, the squid will turn itself inside out, exposing dozens of spiny projections. What could possibly be more horrifying? Imagine if a human did that…



BlobfishSource: bbc.com

While this creature won’t hurt you, it will leave you with wishing you hadn’t agreed to go on that deep sea diving trip. It was even named the world’s ugliest animal at one point and just looking at the picture will tell you why. It’s so hideous that it’s scary!


Humpback Anglerfish

Humpback anglerfishSource: yahoo.com

This deep sea monster lures its prey with a glowing stick that extends from its head.


Dumbo Octopus

Dumbo octopusSource: yahoo.com

Although they may look cute, these guys have been known to envelope their prey with their webbed arms before consuming them.



BarreleyeSource: businessinsider.com

This crazy looking deep sea creature has a transparent head which allows its barrel shaped eyes to stare upwards. Imagine swimming in the ocean depths only to have a transparent head floating towards you with two hideous looking eyes contained within it. Although this fish won’t eat you, it’s unnatural and revolting form is enough to make you regret your encounter.


Stargazer Fish

Stargazer fishSource: yahoo.com

They conceal themselves on the ocean floor with their bulging eyeballs fixed upwards. Then, when an unfortunate fish swims by…they eat it.


Black Swallower

Black swallowerSource: businessinsider.com

Possibly the scariest creature on our list, this fish can swallow prey more than twice its size and over 10 times its mass.

Photos: 25. Marco VinciCymothoa exigua parassita Lithognathus mormyrusCC BY-SA 3.0, 24. wikimedia commons (public domain), 23. © Citron / CC BY-SA 3.0Chlamydoselachus anguineus2CC BY-SA 3.0, 22. animals.wikia.com (fair use; no free images available; illustrative purposes only), 21. Schokraie E, Warnken U, Hotz-Wagenblatt A, Grohme MA, Hengherr S, et al. (2012), SEM image of Milnesium tardigradum in active state – journal.pone.0045682.g001-2CC BY 2.5, 20. Nol AdersMola-mola-Lisboa-20051020CC BY-SA 3.0, 19. pixabay (public domain), 18. opencage, Megamouth shark Megachasma pelagiosCC BY-SA 2.5, 17. Alexei OrlovEurypharynxCC BY 3.0, 16. Dianne Bray / Museum Victoria, Mistukurina owstoni museum victoria – head detailCC BY 3.0 AU, 15. NOAA’s Fisheries Collection , SEFSC Pascagoula Laboratory; Collection of Brandi Noble, NOAA/NMFS/SEFSC, Hollowsnout grenadier ( Caelorinchus caelorhincus )CC BY 2.0, 14. Wikistudent348Sarcastic fringehead (Neoclinus blanchardi)CC BY-SA 4.0, 13. friend of User:BorgxBathynomus giganteusCC BY-SA 3.0, 12-10. wikimedia commons (public domain), 9. Lycaon (Hans Hillewaert), Macrocheira kaempferiCC BY-SA 3.0, 8. wikimedia commons (public domain), 7. © Citron / CC BY-SA 3.0Vampire des abyssesCC BY-SA , 6. InosipmaxBlobFishCC BY-SA 4.0, 5. Javontaevious at English WikipediaHumpback Anglerfish (Melanocetus Johnsonii)CC BY-SA 3.0, 4-3. wikimedia commons (public domain), 2. Canvasman21 at the English language WikipediaNorthern StargazerCC BY-SA 3.0, 1. wikimedia commons (public domain)