Home Sci-Fi35 Nightmare Sea Monsters
Sci-FiBy Joe Burgett -

Man first began to set sail on the sea a little over 10,000 years ago. When this occurred, a lot of new things came about that would become widespread eventually. Mankind came across new and different animals, both big and small. Both could be man-eaters and/or quite ferocious. This led to ancient sailors speaking of horrifying sea monsters for centuries.

Religious texts such as the Torah, Quran, and Holy Bible mention monsters as well as massive sea creatures. Heck, the Bible has an entire story about a man named Jonah being swallowed by a whale, where he stayed for 3 days and 3 nights. Tales like this, both true and exaggerated, are rampant in world history.

Some of these come from real-life accounts that were embellished to help add some sort of mystique or ora around sailing, which only resulted in more people sailing open waters and having their own fun. Sometimes, however, the stories were as real as a heart attack. These tales are the ones we wanted to explore.

Out of all of these horrifying sea creatures from mythology, history, tall tales, and others…which ones come from real-life encounters of actual sea creatures? On top of this, what horrifying sea creatures are still out there today that people can come in contact with?

We’re about to end the myths and set the record straight while also making you want to hold off on that next cruise you were so hyped to go on. These are the real most horrifying sea creatures of all time!

35 Nightmare Sea Monsters
Shipworms Eating Wood [Image via Hakai Magazine]

35. Shipworms

Shipworms may not seem like something you’d consider horrifying, but if you spoke to sailors hundreds of years ago, they might have a different story. The shipworms were well-known during the era of wooden ships, which was at its height for centuries until mankind realized there were several other buoyant materials possible to use.

Shipworms eat through wood, resulting in wooden ships having entire hulls eaten as well as the bottoms of their ships. This is obviously a terrible issue when on the water. They’re not very small like most worms tend to be, they can get pretty sizable, so it’s easy to spot them. There are even giant versions of the species that can get as big as a large tree branch in width. Sadly, by the time people spot them, the shipworms usually have already done some significant damage.

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Sighting of Cosmic Jellyfish [Image via NOAA]

34. Cosmic Jellyfish

Back in 2017, NOAA came across something they ended up dubbing the “Cosmic Jellyfish.” It’s not hard to see why, as it’s quite beautiful and able to draw you in as a result. Now known to science as “Rhopalonematid trachymedusa,” they tend to be at lower sea depths where humans are not likely to frequent. However, they are also quite dangerous.

Like other jellyfish, they have the ability to sting, and even kill. While this often occurs with other marine life, there have been stories of jellyfish, similar to the Cosmic Jellyfish, coming in contact with humans. The ability to draw one in with beauty and then kill is a trait of many jellyfish it seems. The Cosmic Jellyfish proves beauty can be horrifying.

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Goblin Shark caught on camera [Image via YouTube-The Gaming Beaver]

33. Goblin Shark

The Goblin Shark is not very popular, but we have known of its existence since at least 1898. This was when the American Ichthyologist(fish scientist) named David Starr Jordan wrote about them in an issue of Proceedings of the California Academy of Sciences. They tend to live in deeper waters where humans rarely go.

This could be why they are often overlooked on the shark list. They do get their name honestly too. Looking at their facial features, you’d think right off that they look just like a goblin in shark form. That said, we cannot blame anyone for thinking this. Since they are real and can be quite dangerous, they count big time as one of the most horrifying sea creatures known.

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Man Swims With 5,000-pound Bonefish [Image via Reddit]

32. The 5,000lb Bone Fish

In 2017, researchers and scientists were amazed when a massive bonefish was caught. It was later determined to be from the Mola family, under the Mola Alexandrini name. This is a species of Ocean Sunfish. This massive fish weighed in at an astonishing 5,070lbs or 2,300 kilograms. While sunfish can grow to massive sizes at times, this is the biggest ever recorded.

Very little is still known of the species, as the first confirmed sighting of one wasn’t until 2013. The fact that these massive fish species could have been around for a long time and we just truly found out about them is scary. Perhaps some of those old sailer stories hold some truth to them. Something like this proves that amazing can occur at any time in our oceans.

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Mermaid’s Song Poster [Image via GBHBL.com]

31. Mermaids (Well Sorta)

The real story behind mermaids is quite compelling. They were first mentioned centuries ago, and they play big roles in mythological stories. Homer even makes mention of them during The Odyssey. It was believed that these half-human/half-fish creatures were capable of drawing people in with their siren song.

This forced ships to crash attempting to get close or made men want to jump into the waters to meet up with them. It turns out that a lot of these sightings were in areas where the wind was capable of blowing in such a way that it made an almost musical whistling noise. People would sometimes assume they see a human through these often foggy places and get attacked by various animals like manatees and sea lions, as well as some whale species when jumping in.

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Sea Spider moving about [Image via New Scientist]

30. Giant Sea Spiders

While none of the sea spiders is poisonous to human beings or attacks them, they are creepy. Most sea spiders tend to be relatively small, but this is not the case with all. The giant versions of these spiders are usually found in colder waters, which is why Antarctica tends to be where they call home.

When the first photos of one circulated on the internet around 2013, many thought it was fake. Even Snopes claimed it was false. Since then, proven giant sea spiders have been found and even studied by universities here. Their studies found that spiders are able to breathe through their legs, allowing them to take in more oxygen. This, in turn, allows them to grow more.

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Oarfish Held By Philippine Locals [Image via Facebook-Elesa Rosé Jane Allocod]

29. Philippine Sea Serpent

In the Philippines, there was a monster that seemed to just show up out of nowhere one day. It was on the shore, seemingly dead. However, it was unlike any other sea creature locals had seen in quite some time. It made sense, as this fish was massive, managing to reach over 20 feet!

It turns out horrifying sea monsters like this are not really uncommon. The real story behind this monster is that it is merely what is known as an oarfish. These fish can become quite massive, and they are not exactly known for being in this part of the ocean. They normally can be found in the Mediterranean Sea or Atlantic Oceans, not in Pacific Ocean areas like this.

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Folly Beach Beast On Beach [Image via Scribol.com]

28. Folly Beach Beast

The now infamous South Carolina story of the Folly Beach Beast has become quite a tale in the area for the last few years. It all began in 2012 when some sort of then-dead sea species washed ashore in Charleston. It was unlike anything anyone had ever seen before. There was also no species that looked like this in the waters currently, so what was this thing?

Well, it turns out that this horrifying sea monster of sorts was not exactly abnormal nor technically even a monster at all. It happened to be a sturgeon that died, and after so long they develop a look that is kind of monstrous. These fish grow to great sizes as well, so it was not shocking that people were so surprised to see this thing.

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Long-Noses Chimaeras swimming [Image via Fishes of Australia]

27. Long-Nosed Chimaeras

When you talk about some of the most horrifying sea monsters ever, this may not be at the tip-top of the list. However, if you ever came across one in the water, you’d likely feel very different. There is a species roaming the ocean today known to science as the Rhinochimaeridae.

We know them best by the name they have been described as for years, the Long-Nosed Chimaeras. They get the name honestly, as they do tend to have long noses mixed with some weird-looking eyes and teeth. It is honestly frightening to see, making it a sea monster to some. They tend to never grow above 5 feet, but their look alone makes them freaky to most.

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Jasconius carrying boat [Image via Australian Galleries]

26. Jasconius

The Jasconius is well known among the horrifying sea monsters sector due to its popularity in Roman mythology. There are even some who believe it is mentioned in the Holy Bible revolving around the story of Jonah. The story of Jasconius is pretty compelling. Original sailors routinely came across big creatures, often embellishing their stories when told later.

The Jasconius is mentioned by Ancient Greeks who claimed it was able to crack ships in half. Many Greeks assumed the same creature was involved in the connected attacks. The Jasconius likely did exist, but it was nothing more than numerous different large whales they once sailed near. It could be what swallowed up Jonah. However, it was unlikely to be the exact same whale.

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Pelican Eel being examined [Image via Reddit]

25. Pelican Eel

It may be weird, but there are some creatures in the sea that you may rightfully have questions about. Those might be, how the heck is this a thing or what act of Satan gave us this thing? The Pelican Eel likely will fall into this, as it is just the weirdest looking thing you may see in this entire list.

As mentioned, it is obviously an eel. But it has a head that looks almost like an oyster or clam of some kind. The reason for the “pelican” name is likely due to how the pelican looks in the mouth. However, we’re still partial to calling it an oyster-faced eel, so the naming committee can get over it!

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Indonesian Sea Creature washed up on shore [Image via Inverse]

24. Indonesian Sea Creature

A few years ago, a creature washed up on the shores of Indonesia and shocked everyone who saw it. No one local to the area knew what the heck this thing was. What they did know was that it looked really strange and was oozing some sort of red fluid at the time. This blob of sorts was clearly unique looking, but what was it?

Technically, this Indonesian blob is actually a baleen whale. Despite the way the animal appears, this has been confirmed by experts in this area. The reason for its appearance being different is that it has reached very advanced levels of decomposition. When this happens in sea-dwelling animals, they can look incredibly different from their normal appearance.

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A frilled shark swims in a tank [Image via WUNC]

23. Frilled Sharks

Often called the Frill-Toothed Shark by those who come in contact with the species, the Frilled Shark is certainly among the most horrifying sea monsters of recent memory. The species is not exactly worldwide, as they are mostly found around Japan these days. The population is also quite small with many hoping to never come across this species in the ocean.

All sharks can be dangerous and scary, but frilled sharks take things to an entirely different level. They have a face that can only be described as snake-like. It also has a body similar to that of an eel, so it moves around far differently. We did not even have actual footage of the species until 2004, so we’re still learning about this creepy species even today!

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Giant Jellyfish swimming with fish [Image via YouTube-Fat Fish Movies]

22. Giant Jellyfish

There have been many horrifying sea monsters in world history, but very few are as creepy as a Giant Jellyfish. The reason for this is likely due to how creepy jellyfish are, period. Some may look beautiful while others freak you out just by looking at them, but the Giant Jellyfish will truly catch you off guard.

There’s even a name for these things, the Lion’s Mane Jellyfish. The reason for this is that it has some notable tentacles that can, upon movement in the water, look like a Lion’s mane. These jellyfish can grow to the size of a full-grown man! Like other jellyfish, they can sting. However, it has more bark than bite, as the stings from it are not lethal to humans.

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Stethacanthus swimming for food [Image via Faber Courtial]

21. Stethacanthus

The Stethacanthus beast was a very real shark species that lived within our oceans hundreds around 320 million years ago. That makes this species among the first known shark species in existence. The way they looked differed from the multiple types we see today, however.

They had an anvil-shaped fin, which was used for attracting mates and intimidating other potential predators. They were relatively small compared to the larger animals around them. This is why scientists believe they were bottom feeders during their time. However, like sharks of today, they had sharp teeth and strong bodies. This allowed them to take down some bigger animals, especially when attacking in group form.

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Sample of deceased Hatchetfish [Image via Fishes of Australia]

20. Hatchetfish

There are a few different types of Hatchetfish, and this is a big deal to remember as not all of them look the same. There are Marine versions as well as those in deep-sea areas. The most common weirdos are the deep-sea versions, as they can often have nearly ghost-level eyes and teeth that will creep anyone out.

They have creepy teeth and can obviously be intimidating despite their small stature. What makes them creepier than most is their ability to fly..sorta. Hatchetfish jump out of the water a lot, and while they are in the air they can use their fins almost like wings. They don’t fly like birds, but they do get serious air time in their jumps and can even navigate themselves airborne too.

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Thysanoteuthis Rhombus Egg Mass [Image via Smithsonian Magazine]

19. Thysanoteuthis Rhombus

The Thysanoteuthis Rhombus happens to be one of the most interesting sea creatures in the world today. Often referred to by people as the Diamond Squid due to its shape, this also ranks among the most horrifying sea monsters too. They can become very large compared to other squid species. However, their true claim to fame may just be their eggs.

Whenever a Diamond Squid is pregnant and ends up laying out eggs, they do so in something known as an “egg mass” that also has very visible pink egg strands around the overall egg mass itself. These can make the egg mass look somewhat like a big headless sea snake and thus make it horrifying to see randomly in the sea.

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The Infamous hairy blob on Indonesian beach [Image via The Independent]

18. Indonesian Hairy Blob

Back in February of 2017, there was a random hairy blob that washed ashore. It was something big and hairy. It quickly became one of the most horrifying sea monsters to ever be seen in real life for the locals. Nicknamed “The Globster,” no one seemed to know what this thing happened to be.

It measured out to 20 feet in length and around 4 feet in width and weighed in around 4,400lbs or around 2,000 kilograms. It turns out that this happened to be either a Blue or Fin Whale. The muscle fibers were showing during decomposition, resulting in the hair we see.

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Anglerfish from Finding Nemo [Image via The Walt Disney Company]

17. Anglerfish

Do you remember the movie known as Finding Nemo? There is a part of the film where Dory and Marlin go into a very dark part of the ocean, unable to see anything. Suddenly, a monster pops up and turns on the light connected to it. This animal was an Anglerfish!

The Anglerfish is known for being in the dark, deep sea which is why it has a light of sorts that it uses to lure in prey. It really does move throughout the darkness, trying to somewhat influence other fish to check out the random light. It then eats its prey with its really sharp teeth. The Anglerfish looks like the embodiment of evil, honestly. It is truly horrifying, to say the least.

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Believed Look Of The Helicoprion [via The University of Oregon]

16. Helicoprion

The strange-looking Helicoprion is a pre-historic shark species that lived almost 300 million years ago. When fossils were discovered of the shark species, anthropologists and even marine biologists were flat-out amazed by it. The Helioprion has one of the craziest sets of teeth known among any animal species.

They had a spiral set of teeth, forcing many scientists to wonder how they fit them in their mouths. How their teeth seemed to work has been debated for years. What isn’t debated is that this shark likely terrorized the sea of its time, as it was quite large and its now-infamous teeth likely made it a prime predator.

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Bobbit Worm In Attack Mode [Image via SARAWUT KUNDEJ/Shutterstock.com]

15. Bobbit Worms

We’re pretty sure we have already expressed our displeasure with worms. However, the one mentioned earlier does not even scratch the surface when it comes to worms found in the sea. One of the creepiest of all is the Bobbit Worm. In some ways, it can be kind of beautiful as it does have a coloring that is incredibly unique. Yet the beauty just hides the horrors!

They have the ability to turn completely inside and out, and they have sharp teeth. Its teeth are sharp and capable of killing a number of sea creatures. What puts them on our horrifying sea monsters list is that they can actually cut humans, possibly even bite a finger clean off. They can also grow up to a little over 9 feet in length too!

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Sea Monster On Houston Beach [Image via The Washington Post]

14. Houston Sea Monster

After Hurricane Harvey hit the area a few years back, one of the most horrifying sea monsters we’ve ever seen somehow washed up on shore in Texas. It is a large creature with some really sharp teeth. While it was dead upon people seeing it, it was a first for many as very few had ever seen anything like it before.

Local scientists found out our sea monster was nothing more than a Tusky Eel. This eel does not always become this massive but there are cases of them getting to quite a large stature. Also known as the Fangtooth Eel, these horrifying sea monsters swim around in the Atlantic Ocean and the Gulf of Mexico. They are some truly terrifying creatures for sure.

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The Nightmare Lizard Fish [Image via National Geographic]

13. Lizard Fish

While one does not typically expect to see a reptile and fish creature in the same name, you will likely make an exception for the Lizard Fish. It is truly not hard to see why people call it this, as the facial features truly do look like that of a lizard. It is quite possible you have seen one of the numerous different species of Lizard Fish at your local beach.

They tend to live and operate in shallow waters while even those in the deep sea go no further than 400 meters. Despite their lizard-like appearance, they actually are scaleless creatures. They are also transparent, allowing you to see the notable black blotches in their guts. It only serves to make them more horrifying to look at.

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Believed Look Of An Ichthyosaur [Image via Michael Rosskothen/Shutterstock.com]

12. Ichthyosaurs

The pre-historic Ichthyosaurs comes off as an innocent-looking dolphin species. In some ways, this is true as they do look nearly like what a dolphin looks like today. Yet they are not early dolphins at all, as the Ichthyosaurs is a marine reptiles. How did this happen? Through a process called convergent evolution. This involves two species that may look alike through evolutionary stages but won’t actually be related.

This creature was quite large for its time and shares traits with a mackerel and tuna. That means that, for its time, this was likely the fastest creature in the ocean. This is held up by their powerful tails and crescent shape. Their look shouldn’t fool you, as Ichthyosaurs were horrifying and as dangerous as they come. If they lived today, they’d make even sharks afraid of them.

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Believed Look Of The Jaekelopterus [Image via Biomedcentral.com]

11. Jaekelopterus

The Jaekelopterus was an incredibly large sea scorpion that lived just under 400 million years ago. They were among the top apex predators of their time and even ate others of their own species. They were bigger than modern-day humans too, measuring out at 8 feet in length.

The Jaekelopterus were accompanied by massive, spiked claws that were fast and capable of catching anything they wanted. Jaekelopterus are arthropods along with insects, crabs, etc. Thus far, it is the largest ever discovered from this species type. Naturally, you can understand why they are among the most horrifying sea monsters in history.

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The Inspiration For Moby Dick [Image via Balazs Petheo]

10. Moby Dick (Livyatan Melvillei)

The author of the story known as Moby Dick, Herman Melville, actually patterned his story after a real event that was claimed to have happened to a crew of men.  Few believed their sea tale, but after Moby Dick was published, intrigue began to set in making people wonder if this had some truth to it in some way. Was there truly a whale equal to this in history?

The quick answer is yes, and it’s even named after the author of the Moby Dick story. Named Livyatan Melvillei, this species of whale lived around 12 to 13 million years ago. It was the size of a modern sperm whale that ate other whales and anything else they felt like consuming. Modern sperm whales use suction in the water to grab food. However, Livyatan Melvillei operated like Orcas, using their teeth to bite into and tear their prey apart. That novel was certainly not a complete fiction.

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Japanese Spider Crab at an Aquarium [Image via Reddit]

9. Japanese Spider Crab

The Japanese Spider Crab is one of the freakiest sea creatures to date. First and foremost, it is important to note that this is a real crab that you can likely see at some zoos. If not, you can visit the coasts of a few Asian territories like Japan where you can likely come across some of them.

The name of the crab comes honestly, as the legs of the crab look just like regular crab legs. Except for the weird fact that they are insanely long. This makes them come off as spider-like, hence the Spider Crab name. They are horrifying sea monsters to most just based on appearance. However, they are unlikely to go after humans.

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Artist Rendering Of Possible Levithan look [Image via Daniel Eskridge/Shutterstock.com]

8. Leviathan

For centuries, there have been several legends surrounding a creature known as the Leviathan. It is often mentioned by the Jewish in older texts. The Holy Bible even mentions the Leviathan in the Books of Job, Isiah, and Amos as well as in Psalms. Was this creature real, if so, what was it? Some believe Leviathan was used as a metaphor for a powerful enemy.

Others believe it to be very real. Most now believe it was more than likely a giant whale. Centuries ago, there was some speculation that whales were a little larger in some parts of the world, even over what we see now. Levithan likely was one of those larger whales, obviously embellished a bit over time.

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Caught Ghost Shark In Woman’s Arms [Image via Live Science]

7. Bucktoothed Ghost Sharks

The Bucktoothed Ghost Shark ranks as one of the most horrifying sea monsters out there. Funny enough, despite their name, this is actually not a species of shark. Although related to them, they technically belong to the Chimaera family. Many from this family are creepy for sure, but the ghost shark really takes the cake.

There are numerous different versions of ghost shark, but we feel the bucktoothed version is likely the creepiest. It often has a darker coloring, usually black. The teeth are all sorts of jacked up and it looks like it escaped a fish mental facility. It is clearly one ugly fish that will freak you out if you see one in the water.

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Artist Rendition Of A Liopleurodon [Image via Daniel Eskridge/Shutterstock.com]

6. Liopleurodon

The Liopleurodon was a creature that lived during the Jurassic period, several million years ago. Like others, it was not technically a fish or natural sea-dweller. The Liopleurodon was a giant marine reptile. In the water, there were very few predators that could go up against them and live.

They grew up to 30 feet in length normally but there are fossils that seem to indicate that some grew even bigger than this. In studies of the species, we have been able to find that they had some incredibly big and sharp teeth that could rip through anything they chose to attack. They were very fast for their size and even had a great sense of smell that they used to find prey.

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Plesiosaurs, The Inspiration Behind The Loch Ness Monster [Image via Catmando/Shutterstock.com]

5. Loch Ness Monster

For several years, we have heard tales of a creature native to Loch Ness in Scotland. It has been described in numerous different ways, but the most common description paints an image of the long-extinct Plesiosaurs. They are considered the main inspiration for Nessie today, so it is possible that something like it lived in Loch Ness over one hundred million years ago.

There have been cases of animals living longer than originally assumed. Woolly Mammoths are the best example of this. We thought they went extinct well over 10,000 years ago. However, it turns out that they lived thousands of years longer and would not truly go extinct until 4,000 years ago. Could the Plesiosaurs be similar to this? Could one have lived long enough to be seen once by someone who then started the legend?

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Artist Rendition Of A Dunkleosteus [Image via Leotrex-Artstation]

4. Dunkleosteus

The Dunkleosteus is one of the most unique creatures ever discovered. The species lived around 400 million years ago and were among the top apex predators of their time period. They routinely preyed on sharks and other predators, likely any of those mentioned on this list if they were around.

The Dunkleosteus had armor-like plating, making them impossible for other predators to truly battle against. They had one of the single strongest bites ever recorded. Scientists measured this out and determined they were able to bite with a pressure of 8,000 pounds per square inch. This is on par with the Tyrannosaurus Rex!! That is only measuring from the tip of its fang too. Phew! They were 33 feet long as well. All of this made them one of the most horrifying sea monsters known.

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Artist Rendering Of A Possible Kraken [Image via Daniel Eskridge/Shutterstock.com]

3. Kraken

We’ve all heard the legend of the Kraken. It was a sea monster mentioned for hundreds of years by sailors all over. They were most commonly linked to pirates who told tall tales consistently. Yet the story of the Kraken first began with the Vikings. It is widely believed that the tale of the Kraken comes from real-life accounts of giant squids.

We know it is possible that Vikings would have come across giant squids in their travels. Of course, stories about their sea travels could take on a life of their own. This is likely why the Kraken took off and ended up being used in numerous fictional stories. The fact that the origin began from real giant squids, likely found in the waters of Norway and Greenland, is very compelling.

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A Mosasaurus In The Jurassic World Film [Image via Universal Pictures]

2. Mosasaurus

If you have seen the movie Jurassic World, it is very likely you are familiar with the Mosasaurus. Remember the animal that jumped out of the ocean to attack another dinosaur flying through the air and even a shark in a Seaworld-like environment? If you do, that was a Mosasaurus.

They were giant reptiles that could choose to swallow prey whole or cut them up with their amazing teeth. The Mosasaurus was bigger than many of the biggest land dinosaurs known. They were also quite different from other reptiles. Scientists found that baby Mosasaurus spent their early life in the open ocean, making some believe that the species gave birth to live young and not via eggs.

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Megalodon Size Comparisons [Image via Catmando/Shutterstock.com]

1. Megalodon

We always hear about the Megalodon during Shark Week on Discovery Channel, but it is for a good reason. The Megaladon species has fascinated humans for years. Just think, a giant shark? Sharks now are horrifying but if the Megaladon lived today it likely would trump all other horrifying sea monsters in the world.

They measured in often more than 50 feet in length! The jaws of the shark were so large that grown adults could walk through the opening. The species was known to hunt whales, as they were likely the only big meal they could get. It is widely believed that the extinction of the Megalodon is what allowed whales to grow so large. Without another species cutting them down, they were only able to grow. The last known Meg died 3.6 million years ago, which is eery as early humanity began at this time.



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The Weird-Looking Striated Frogfish [Image via Francesco_Ricciardi/Shutterstock.com]

Striated Frogfish

The Striated Frogfish is certainly one of the most horrifying sea monsters we’ve seen. They are found all across the Atlantic Ocean as well as the center of the Pacific Ocean. The Frogfish have even been known to show up in the Gulf of Mexico, the Caribbean, and the western coast of Africa. They tend to mostly live in tropical or subtropical waters, so when it gets cooler in one area they will navigate toward the warmer climate. 

Despite only reaching less than 9 inches in length, the Frogfish is certainly startling. You’ll note that its extensible body and awkwardly arranged dermal spinules are freaky. Yet what makes them even odder is the forwardly extended jaw that allows them to swallow prey whole. They can even swallow creatures as big as themselves!! The species can also change color, especially when going into new environments. It takes Frogfish only a few weeks to change to their surroundings.

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Animation Of Vicious Green Moray Eel [Image via Konstantin G/Shutterstock.com]

Green Moray Eels

On their own, eels are creepy. However, the Moray Eel family is known to be possibly the creepiest due to both where they reside and how large they can get. The most notable of the Moray Eel family is the Green Moray. Often called this due to their coloring, they can also be yellow and thus called Yellow Morays. It is a bit complicated, we know.

These particular eels tend to be located in the Atlantic Ocean from roughly New Jersey to Bermuda while also being spotted in the Northern sector of the Gulf of Mexico to South America. They are capable of reaching 2.5 meters in length or slightly over 8 feet. You’ll also see them usually in the mid-depths of the ocean, around 40 meters in or just over 131 feet deep. They can startle even the most seasoned deep divers, with their razor-sharp teeth that could rip through them if it wanted.

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Japanese Giant Salamander Swimming [Image via Martin Voeller/Shutterstock.com]

Giant Japanese Salamander

While some might claim that using a salamander for an article about horrifying sea creatures is cheating, we could not disagree more. This salamander is often found in the waters of Japan and happens to be closely related to the Chinese Giant Salamander too. Usually, Salamanders can look a lot like lizards but people may not be able to tell them apart.

However, the best way to do so is pretty much the skin and environment they inhabit. Their skin will be soft and almost feel like waterproof coatings. That is due to their watery habitat. Lizards do not live in or very near the water. The Giant version in Japan is capable of getting up to 5 feet and weigh around 55lbs. This is compared to the normal salamander that gets to maybe a foot or two and less than 10lbs. Coming across one of these guys in the wild could be horrifying.

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Drawing Of Vampire Squid [Image via Field Museum]

Vampire Squid

We actually did not use the entire name for this creature in the header, but it’s worth noting that it is actually called “The Vampire Squid from Hell.” As one can tell, it has many fans. It does not get very large but it’s often hard to tell what it is. It looks like a cross between an octopus and a squid and even has a higher connection to octopuses. Why is it called a squid? It is thought to appear like some types of squid from the past.

In fact, it’s the only surviving creature of the Vampyromorphida family. It is widely assumed that this creature, due to being in the extreme deep sea, never truly evolved. That is why many call it a phylogenetic relict. It is often called a “Vampire” Squid for one reason. Its coloring gives it the appearance of a black coat or cloak like Dracula. It does not suck blood but you never know with some of these deep-sea creatures.

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The nightmarish Deep-Sea Dragonfish [Image via Fine Art America]

Deep-Sea Dragonfish

Few know how the Dragonfish got its name, but some feel it is due to the coloring that gives it an eerie appearance. Yet some point to the teeth it has, which are massive and capable of ripping into human flesh if it so desired. It is highly unlikely a human being would come across one in the wild, however. The Deep-Sea Dragonfish earned its name honestly, as it’s located deep in the ocean.

They do not get very large, as they reach roughly 15cm to 26cm or around 5 to 10.5 inches. In spite of their small size, they are considered apex predators in the deep-sea. This is due to their absolutely massive jaws, that are completely filled with teeth sharp enough to cut through just about anything it chooses. Due to their cranium and upper-jaw, they can open their mouths up to 100 degrees, allowing them to kill and swallow large prey. Even those more than 50% larger than it.

35 Nightmare Sea Monsters
Stargazer Fish Waiting For Prey While Buried In The Sand [Image via Ethan Daniels/Shutterstock.com]


The Stargazer fish species is relatively large, with around 51 confirmed types known. They are only in saltwater and tend to be found in both shallow and deep water. Thus, they have come across humans quite often. The Stargazer gets its name from the eyes located on the top of their heads. Although, we like to think it also looks up at the stars sometimes too. The name also comes from how it catches prey!

They have a large, upward-facing mouth that they hide while burying themselves in the sand as they wait for prey. Just their weird-looking eyes will be visible and they’ll ambush prey that comes by. The species is also venomous due to its large spines just above their pectoral fin sector. It is said that their venom likely could not kill a human unless they are cut open by a lot of Stargazers or the person is allergic. Yet they are still horrifying sea creatures to look at!

35 Nightmare Sea Monsters
Giant Ottoia In Deep Rising Film [Image via Buena Vista Pictures]


While there are actual Ottoia creatures out there, for a long time they became the nightmare creature to think about. Why? Due to how they were utilized in books or movies. Ottoias are relatively small but what if they became gigantic?!? In the movie Deep Rising, an Ottoia creature named Argonautica showed up and scared a lot of 90s kids in 1998.

The concept of the character in the film is that it is simply an evolved version of the Cambrian Worm, which we know as the actual Ottoia. Yet if you see the movie, what they do with the character makes it one of the most horrifying sea creatures imaginable. They give it the traits of an actual giant Cambrian Worm while also making it come off similar to the Kraken. Oh my!

35 Nightmare Sea Monsters
Realistic Version Of Pokemon Gyarados [Image via Pinterest]


We know what you’re thinking, did they just add a Pokemon to this list? Yes, yes we did. The Gyarados is often used in Anime, which kind of takes away a lot from how horrifying it would be in real life. This is why we wanted you to see a more realistic version of the creature, should it be seen in person. As you can see, it is quite large. 

This Water Type Pokemon is capable of using water abilities to take down opponents or prey. While it is quite a notably fast swimmer and impressively strong in the water, the Gyarados can also fly. Thus making it a dual-threat! It typically reaches a little over 6 feet in height as well as 230lbs+ in weight. Overall, it is not one to mess with. In real life, it would likely result in the extinction of mankind.

35 Nightmare Sea Monsters
Jörmungandr In God of War video game [Image via Sony Interactive Entertainment]


Those who know about Norse Mythology know all about the Jörmungandr. Of course, those who play the God of War video games might also know of it too. Those games revolve around the Greek/Roman Gods in Mythology, so connecting Norse Mythology to things made sense. The versions you might read about differ depending on where it’s used.

You might also know it a bit from Marvel Comic books or films involving Thor, due to his connection in mythology to it. In Norse Mythology, the Jörmungandr (also known as the Midgard Serpent) is so long that he can wrap all the way around Earth or “Midgard.” He keeps his tail in his mouth, almost as a protecting shield. As the offspring of Loki and Andrboda, once the serpent releases its tail, “Ragnorok” begins. In Mythology, Thor battles and slays the serpent, dying in the process.

35 Nightmare Sea Monsters
Colossal Squid Washed Up On Shore [Image via Adéle Grosse/Iziko Museums of South Africa]

Colossal Squid

While we’ve had a lot of fun discussing some biblical, mythological, or fictional nightmare creatures of the ocean, there is one that is very real and capable of dealing a lot of damage if it desires. Originally discovered in 1925, most did not believe it was true. We found out over the years that they are very real and they tend to be located in the cold, Southern Arctic Ocean.

They can reach a little over 1,000lbs or 490+ kilograms on average. Meanwhile, the largest known have weighed between 1,300 to 1,500lbs or 600 to 700 kilograms. In length, they have been known to reach between 30 to 33 feet or 9 to 10 meters. While one would assume they’d kill prey easily due to their size, they actually tend to be ambush predators and use bioluminescence, or the production of light, to capture prey.