Top 20 Deep Sea Mysteries That Will Freak You Out
Trivia Top 20 Deep Sea Mysteries That Will Freak You Out



Top 20 Deep Sea Mysteries That Will Freak You Out

VOICE OVER: Rebecca Brayton WRITTEN BY: Michael Wynands
71% of the planet's surface is covered in water. That's a whole lot of space for secrets to hide. For this list, we'll be looking at a variety of curious, compelling or even sinister deep sea discoveries and oceanic enigmas.

Top 20 Deep Sea Mysteries That Will Freak You Out_S5S2W3

71% of the planet’s surface is covered in water. That’s a whole lot of space for secrets to hide. Welcome to WatchMojo, and today we’ll be counting down our picks for the Top 20 Deep Sea Mysteries That Will Freak You Out.

For this list, we’ll be looking at a variety of curious, compelling or even sinister deep sea discoveries and oceanic enigmas.

#20: Gulf of Mexico Shipwreck

In May of 2019, a group of researchers from the National Oceanic and Atmospheric Administration were conducting tests with underwater drones in the Gulf of Mexico when sonar picked up this mysterious wreckage. Marine archaeologists across the globe were immediately contacted to watch via livestream as the drone explored the ship. Apart from the number “2109” the researchers were unable to identify much about this ship of unknown origin. It’s estimated to have been constructed 200 years ago, and based on the charred timber, it was likely burning when it sank. What tragic fate befell this vessel? Here’s hoping we can learn more as NOAA [note for VO: pronounced “Noah”] continues to investigate. Either way, it’s in good company - the gulf is home to many such mysterious vessels.

#19: A Deadly Undersea Lake

We generally think of all water within a given space as being homogenous, but variables like temperature and the salinity levels can create entirely distinct sections - like lakes in oceans! At the bottom of the Gulf of Mexico, 3,300 feet below the surface of the ocean, researchers have found just such a body of water. 12 feet deep and roughly 32 feet across, this undersea lake might be small, but it certainly packs a punch. Dubbed the “Jacuzzi of Despair”, it kills any sea creature foolish enough to test its depths. This highly salinated water, rich in methane and hydrogen sulfide, is seriously toxic. Little is understood about this surreal undersea environment, but researchers think it might give insight into the conditions on extraterrestrial planets.

#18: Julia Sound

Recorded in 1999, “Julia” is the name given to a mysterious sound picked up by the U.S. National Oceanic and Atmospheric Administration. It only lasted 15 seconds, but it captivated the scientific community and amateur theorists alike. NOAA suggested that it most likely originated from an iceberg colliding with the landmass of Antarctica, but this can’t be proven. What we do know is that it was loud enough to resonate across a massive section of the ocean. Those willing to consider more “out there” possibilities have suggested that it could be the sound of a massive unknown creature. Rumors abound about NASA satellite photos showing a huge shadow moving in the waters off of Antarctica around that time, but no such images have surfaced.

#17: Adam's Bridge

Rama Setu, also known as Adam’s Bridge, is a series of limestone shoals that form a rough connection between the northwest coast of Sri Lanka and Pamban Island, 30 miles away. The history of Rama Setu is intertwined with local legend. According to Hindu lore, it was built by an army of warrior monkeys known as “Vanara” to help the god Rama save his wife Sita from the Demon king Ravana. While this origin story is widely treated as myth rather than reality, there are those who assert that Adam’s Bridge was in fact built and was never a naturally occuring land bridge. All we know for sure is, back in the 15th century, it was entirely above sea-level and traversable.

#16: Macropinna Microstoma

Think that’s a weird name? Wait til you see the fish it belongs to! First discovered in 1939, this mysterious and thoroughly alien-looking creature wasn’t photographed alive until 2004. It spends its life at depths between 2,000 and 2,800ft, and though its been caught a number of times over the years, its fragile anatomy has made it incredibly challenging to study. From the “barreleye” family, Macropinna microstoma has a translucent domed head, which, coupled with its unique tubular eyes, gives it an advantage over its prey. The tubular eyes are extremely well-suited for capturing light in its dark habitat, while its domed head allows it to not only forward, but also up through its own head. Unique? Sure, but also super creepy-looking.

#15: Gulf of Khambhat Ruins

Discovered in the early 2000s, these alleged ruins are still generating controversy decades later. Located off the coast of Gujarat in the Gulf of Khambhat, this archeological site is seemingly made up of city-like structures and home to various artifacts. But because the area was dredged rather than being explored via more careful methods of excavation, the scientific community is divided as to the significance of the results. The structures are compelling, but the relevance of the carbon-dated materials from the site is hotly debated. If they are indeed the tools of an ancient settlement, dated at 9,500 years old, that would make the Gulf of Khambhat ruins the oldest known civilization.

#14: Australia’s Cannibal Shark

Just as lions rule the savannah, great white sharks rule the seas. Okay, technically, killer whales have been known to target them, but that’s not what happened here. Australian scientists were shocked and utterly perplexed when a 9 foot long great white shark was apparently devoured. It had been tagged with a tracker as part of a study, and when said tracker washed up on-shore, the data contained within showed a sudden spike in temperature followed by a staggering 1,900 dive. After careful investigation, the researchers were left with only one possible conclusion: it was eaten by a cannibal shark of the same species estimated to be 16 foot long and two tonnes! Terrifying, right?

#13: Baltic Sea Anomaly

In 2011, Swedish diving team “Ocean X” were searching for sunken treasure in the Gulf of Bothnia. They stumbled instead upon something far stranger. Using sonar equipment to take a rough image of the object, they reported that it was 200 ft in diameter and bore distinct design patterns that seemed unnatural. Adding to the mystery of the Baltic Sea Anomaly is the fact that, according to the team, there was electrical interference in the area, preventing them from getting a clearer image. The team has even suggested that it could be a UFO. Needless to say, scientists are sceptical. It doesn’t hurt though that the structure looks vaguely like the Millenium Falcon or Ebon Hawk from Star Wars.

#12: Light Wheels in the Persian Gulf

We’re starting to notice a pattern here. If you’re on the hunt for an oceanic mystery of your very own, explore a gulf! Sometimes poetically referred to as “ghosts of the ocean”, light wheels are large glowing circles of light that appear on the water and have been observed for decades; some reports actually go all the way back to the 18th century. Often measuring hundreds of feet in diameter, these eye-catching anomalies have been explained away (most notably by oceanographer Kurt Kalle) as the result of bioluminescent plankton and seismic waves. While plausible, such theories struggle to explain the variety of shapes that the light wheels take, or the fact that they appear to spin at varying speeds.

#11:The Milky Seas Effect

Sailor’s tall tales are often dismissed as mere superstition. Well, the Milky Seas Effect is one story that we can confirm - even if we don’t entirely understand it. Historically, sailors have reported seeing large sections of the sea become a pale milky white (or blue) and emit a faint glow. Now, thanks to modern technology, we know that the milky seas effect is not only real, but the result of bioluminescent bacteria. While that’s all well and good, we still can’t figure out what causes these sudden explosions in bacterial populations or the other variables that result in this unique sight.

#10: Leptocephalus Giganteus

Described by Anton Bruun in 1930 and Peter Henry John Castle in 1959, Leptocephalus Giganteus is an extremely rare species of eel thought by some to swim the ocean depths. Only two such specimens have ever been studied and they were in the larval state, meaning that they were nowhere close to reaching maturity. But even as a larva, one specimen was roughly 6 feet in length. And given that eel larva is typically 1/32nd of its adult length, that would suggest a truly monstrous eel come maturity. Now, contemporary scientists have suggested that Leptocephalus Giganteus was likely misidentified and would not not grow substantially beyond that point, but without further study, it’s impossible to say! Leptocephalus Giganteus could be the reality behind sea serpents.

#9: Aegean Sea Ruins

In 2015, researchers hailing from Greece and Sweden made one of the most remarkable archaeological discoveries of the 21st century. Working south of Athens in the Kiladha Bay, the team was exploring fertile territory; the area is rich in archaeological sites. But nothing could have prepared them for what they found. What began with a few pottery fragments led researchers to uncover the ruins of an entire lost city - one that occupied somewhere in the ballpark of 12 acres of land. The city dates back to the Bronze Age and was seemingly protected by a wall complete with defensive towers - structures unseen until now in any other ancient Greek sites. How this seemingly once-great city fell, however, is anyone’s guess.

#8: Colossal Squid

This terrifying deep sea beast was first discovered in 1925, and its existence admittedly lends a certain credibility to all those myths about sea monsters. Because colossal squids are so elusive, our knowledge of their anatomy is somewhat limited, but based on beaks that have been recovered, it’s been hypothesized that, at maturity, they could weigh up to 1,500 lbs and measure 30 to 33 feet in length. Only a handful of specimens have ever been found, which makes sense given that they generally inhabit the Antarctic Ocean and dwell at depths of up to 7,200 feet. As if the colossal squid’s size wasn’t intimidating enough, they’re armed with both swivelling and three-pointed hooks on their limbs.

#7: The Ruins of Dwarka

The lost city of Dwarka is one of the rare instances of a myth possibly being confirmed as fact. According to legend, the Hindu Deity Krishna founded the now legendary city of Dwarka long ago. The city is sacred in the Hindu faith, and is said to have been unparalleled in its beauty and splendor - rich in greenery, wildlife, and palaces. It was utopia - that is until it was swallowed up by the sea. The Dwarka of legend has understandably long been dismissed as a work of fiction, but in the 1980s, with the discovery of underwater ruins off the coast of the modern day coastal town of Dwarka, people were forced to reconsider that assumption. The research continues to this day.

#6: The Bimini Road

Dubbed the “road to Atlantis”, the Bimini Road (or Bimini Wall, as some would argue) is a rock formation that runs for a half mile underwater in the Bahamas. Located near North Bimini Island, this mysterious marine landmark is made up of large, roughly rectangular limestone blocks which seem to form a road or wall-like pattern. Analysis of the stones, including carbon dating, has led researchers to conclude that the Bimini Road is a natural formation resulting from erosion and the currents. But… given that there are two other similar patterns in the area, and considering the fact that some of the stones appear to be stacked atop one another, there are some who maintain that there’s more to the Bimini Road than carbon dating suggests.

#5: The "Atlantis of Japan"

Various underwater ruins around the globe have been posited as the “lost city of Atlantis” upon their discovery. But if there’s one that leads the pack, it’s the Yonaguni Monument. As with the Bimini Road, many have dismissed these underwater rock formations as being naturally occuring. But the structure is oddly geometrical, and includes reliefs that vaguely resemble animal carvings, and what appears to be the remnants of columns. As such, there are some, like Professor Masaaki Kimura, who have argued in favor of this being the remnants of a lost civilization, possibly even the lost continent of Mu (another name for Atlantis).

#4: Bloop

The “Julia” recording certainly made waves in the scientific community, but if there’s one deep sea sound file that people never seem to get tired of debating, it’s the “Bloop”. And it’s not just scientists versus conspiracy theorists - not even researchers within relevant fields seem to be able to agree about its origins. This ultra-low-frequency, high amplitude sound was recorded in 1997. First, it was speculated that the sound was caused by icebergs dragging along the ocean floor. But then, in 2002, Christopher Fox of the National Oceanic and Atmospheric Administration speculated that it had been produced by an animal. Flash forward another 10 years and the NOAA was once again pointing towards ice quakes.

#3: The Megalodon

Human history, across various cultures, is chock full of myths and legends about sea monsters that tormented sailors of yesteryears. Unlike the Leviathan or the Kraken however, we know for a fact that the Megalodon once swam these seas. The word “megalodon” literally means “big tooth”. Measuring up to 59 feet in length and reaching upwards of 59 metric tons, these prehistoric terrors certainly earn the name. The general scientific consensus is that they went extinct millions of years ago, but there are those who believe that they continue to survive in secret. And it’s not just Discovery Channel fueling the speculation - species like the Coelacanth and megamouth shark remind us that anything could lurk in the ocean depths.

#2: The Lost Submarines of 1968

Life aboard a submarine isn’t for the faint of heart. You’re literally trapped in a long metallic cylinder hundreds of feet below the surface of the ocean. When something goes wrong... it often goes very wrong. Despite the inherent risks however, four such vessels going missing in quick succession makes for an incredible coincidence. With 318 lives and four subs lost in a single calendar year, 1968 is the most deadly year in submarine history since the end of WWII. The USS Scorpion, the INS Dakar, the Minerve, and the K-129, hailing from the States, Israel, France and the Soviet Union respectively, all disappeared under mysterious circumstances and continue to be the subject of speculation decades later.

#1: The Bermuda Triangle

Roughly defined by Puerto Rico, Miami and the island of Bermuda, this triangle is the subject of much superstition. For the record, this is among the most heavily traveled stretches of ocean in the world, and most trips are completed without incident. But... the accidents and disappearances that have transpired are notably strange. The Ellen Austin incident allegedly saw not one, but two crews disappear from a derelict ship found in the triangle. The USS Cyclops was a US Navy ship that disappeared with all 309 sailors. There are countless such stories, leaving an enduring shroud of mystery over these stormy seas.