One of the coolest pieces of irony about our planet is that the ocean covers most of the surface of the Earth, and yet, the vast majority of it is still unexplored! So, you can bet your bottom dollar that there are tons of unsolved mysteries linked to anything ocean-related.
We wanted to give you a bit more appreciation for just how bizarre and puzzling things beneath the waves can get. So, our team at Bored Panda trawled the digital seas for the biggest, most tantalizing ocean enigmas that have researchers scratching their heads to this very day. Scroll down to dive in.
#1 Baltic Sea Anomaly
In 2011, while exploring the Baltic Sea floor, Ocean X Team, a company specializing in deep-sea exploration, searching for lost treasure, historic shipwrecks, and underwater anomalies, discovered a strange object 200 feet in diameter, resembling the Star Wars’ “Millennium Falcon” landing on the Baltic seabed.
Even stranger, while the research team was above the object, they experienced interference with the communications system. As soon as they moved a few hundred feet away, everything worked again. Scientists who obtained soil samples claim the object is purely natural. But why, then, was there interference? The researchers have no answer yet.
Image credits: Hauke Vagt, Brooke Morton
#2 Submarine Disappearances In 1968
1968 remains a year of mourning for submariners worldwide. In just six months that year, four submarines sank: the USS Scorpion (SSN-589), the Soviet K-129, the French Minerve, and the Israeli INS Dakar, taking the lives of 318 people overall.
Each submarine accident had its own unique details, and many of them remain a mystery to this day.
Image credits: imaginima
#3 The HMS Daedalus’ Sea Serpent
In 1848, HMS Daedalus was off the coast of present-day Namibia en route to Saint Helena when Captain McQuhae and many crew members saw what they described as a sea serpent in the water.
“The creature passed rapidly, but so close under our lee quarter that had it been a man of my acquaintance I should have easily recognized its features with its naked eye,” Captain McQuhae recalled.
According to eyewitnesses, the creature could’ve been up to 60 feet long and swam at speeds of 12 to 15 miles per hour. Today, some researchers assume that the seamen simply saw a sei whale – but this is far from certain.
Image credits: https://commons.wikimedia.org/
The ocean, the biggest livable space on Earth, covers more than two-thirds (around 70%) of our planet’s surface. And yet, according to NOAA Ocean, most of the ocean remains unmapped and unexplored.
As of June 2025, 27.3% of the world’s seafloor had been mapped. Though this seems like very little, the upside is that we’re learning more about the ocean every year.
One of the reasons why progress can be quite slow is that 90% of the ocean is deep ocean, deeper than 200 meters or 656 feet, making it challenging to map with current technology.
#4 The Bermuda Triangle
The Bermuda Triangle is a notional figure in the Sargasso Sea, with Miami, Bermuda, and Puerto Rico as corners, where several dozen ships and planes have disappeared in recent decades.
Experts cite unexpected methane emissions, so-called rogue waves, and infrasound, which can sometimes be generated at sea, driving sailors and pilots crazy, as the probable causes of these mysterious disappearances.
These are the most rational explanations, while other fantastical possibilities include abductions of ships and planes by UFOs, attacks by giant sea creatures, and so on. However, none of these cryptotheories have yet been confirmed.
Image credits: commons.wikimedia.org
#5 The Stronsay Beast
In 1808, after a storm, the carcass of a gigantic, unidentified creature washed ashore on the island of Stronsay in the Orkney Islands. Local farmers measured it and determined it was 55 feet long – and that’s without its tail, part of which was clearly missing!
Local naturalists were unable to identify the remains, but later biologists concluded that it may have been part of a giant shark. According to eyewitness accounts, the creature had three pairs of limbs, its ribs were lined with bristles, and a “mane” of bristles ran along its entire back. The bristles glowed in the dark when wet, and its stomach contents were red.
Overall, the creature’s description is somewhat similar to the words of people who allegedly saw the Loch Ness Monster more than a century later. However, the Stronsay monster is described as having a cartilaginous rather than bony skeleton – which clearly indicates that we’re dealing with the remains of a shark, rather than something unidentified.
Image credits: Sydney Moore
#6 The Island Of Bermeja
Bermeja was a small phantom island off the coast of the Yucatán Peninsula. It has appeared on maps since the 16th century, but expeditions at the end of the last century failed to confirm its existence. Rising sea levels are a possible cause of the island’s disappearance.
However, there is another theory: some Mexican politicians and activists do claim that the Americans simply “blew up the island” to shift the boundaries of the US exclusive economic zone and include the Hoyos de Dona oil field.
Some Mexican divers have claimed to have found the remains of the island underwater at a depth of approximately 120 feet, but no detailed scientific expeditions have yet been conducted there.
Image credits: commons.wikimedia.org
National Geographic warns that global warming leads to rising ocean temperatures and sea levels, drastically changing ecosystems. For example, cold-water habitats are shrinking, affecting animals like penguins, seals, and whales. Meanwhile, this affects plankton, too, meaning there are fewer of them available as a food source for marine life.
Pollution is a massive issue, too. Some of the biggest sources of pollution come from oil runoff that flows into the ocean, chemical runoff, sewage, plastics, and carbon dioxide.
“Although the ocean is vast, it is more easily polluted and damaged than people once thought. It requires care and protection as well as expert management. Only then can it continue to provide the many resources that living things—including people—need,” National Geographic states.
#7 Mystery Of Giant Ice Circles
From time to time, astronauts have noticed large, mysterious circles on the ice of Lake Baikal in Siberia – at least in the winters of 1986 and 1994. Speculation immediately arose that these circles were artificial, supposedly left by aliens.
Scientists are once again attempting to debunk the sensationalists’ efforts, claiming that these circles are simply the result of methane emissions from the lake bed. These emissions heat up the water and cause it to swirl due to Coriolis force from the Earth’s rotation.
Sometimes the ice is too strong for warm water to melt it, but these giant concentric marks remain.
Image credits: ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Center.
#8 Kaz II, Dubbed “The Ghost Yacht”
In April 2007, the yacht Kaz II was found drifting near the Great Barrier Reef off the coast of Australia. Everything on the yacht appeared as if the crew was still on board – except that none of the three crew members were!
There were various theories that all three drowned while rescuing one of the crew members, or were kidnapped by another vessel, but to date, no bodies have been found or any confirmation of either theory.
Image credits: Ian Hitchcock
#9 The Giant Cannibal Shark
In November 2003, a female great white shark, previously tagged by researchers, inexplicably disappeared. According to data from the tag, the fish suddenly dove to a depth of 1,903 feet, and the surrounding water temperature rose from 46°F to 78°F. Apparently, it was a surprise attack.
Given that cannibalism is sometimes observed among great white sharks, scientists seriously believe that the female was simply eaten by another, larger and more aggressive shark.
Image credits: Berthold Grünhagen
What do you think, dear Pandas? Are you as fascinated by the ocean as we are? What are the coolest facts you know about the ocean?
Meanwhile, what are the most bizarre ocean-related mysteries that you’ve ever heard while growing up? What do you think scientists could do to advance ocean exploration at a faster pace?
Tells us what you think in the comments.
#10 Mysterious Ocean Sounds
In 1960, the scientists recorded a series of sounds in the Southern Ocean off the coast of Antarctica – like those of a giant duck quacking underwater. That’s why the sound was actually nicknamed “Bio-Duck.”
For many years, researchers have tried to figure out who or what is the source of these sounds. Today, science believes that these sounds are produced by Antarctic minke whales. At the very least, their “songs” are very similar to “bio-duck” sounds.
The question remains: why are these same sounds sometimes heard in parts of the ocean where Antarctic minke whales aren’t found? But scientists are confident that they will figure this out sooner or later.
Image credits: Sergio Kian
#11 The Devil’s Sea
The Pacific Ocean has its own equivalent of the Bermuda Triangle – the so-called Devil’s Sea (“Manoumi”), a triangle northeast of the Philippines that has long had a notorious reputation among Japanese fishermen. In recent decades, numerous ships and planes have disappeared there.
Some blame paranormal phenomena. Others simply believe the sea is too difficult to navigate (and, incidentally, quite congested with shipping routes). Whatever the case, this section of the world’s oceans is no less strange and dangerous than the Bermuda Triangle.
Image credits: Divya Ramachandran
#12 The Yonaguni Monument
In 1986, Kihachiro Aratake, director of the Yonaguni-Cho Tourism Association, discovered a strange underwater hill during a scuba diving expedition on the Japanese island of Yonaguni, shaped like a typical ziggurat, surrounded by landforms resembling building structures.
Over the following decades, Yonaguni Island was visited by several expeditions. Some scientists dismiss these as simply bizarre underwater landforms, claiming the “monument” is composed of sandstone that tends to crack at right angles.
Some are sincerely convinced that the Yonaguni Monument is a relic of a lost ancient civilization, similar to Mu or Lemuria. According to research, approximately 10K years ago, the area where the monument is located was above sea level – a fact that only adds to the excitement of those seeking lost civilizations.
Image credits: commons.wikimedia.org
#13 The Kraken
Since ancient times, seamen sailing the waters of the North Atlantic brought back bone-chilling legends about the Kraken. A giant, bloodthirsty octopus, capable of sinking any ship with its tentacles, randomly choosing its victims among sailors. A merciless giant from whom there’s no escape at sea.
Today, we are almost certain that these legends had a certain rational basis – at the very least, many giant squids are larger than ancient ships. On the other hand, no giant squid actually attacks humans… In short, the Kraken remains simply a beautiful mystery and legend.
Image credits: commons.wikimedia.org
#14 Mary Celeste
On November 5, 1872, the cargo ship Mary Celeste, en route from New York to Genoa with a cargo of alcohol, was found adrift in the ocean with no sign of crew or passengers (the captain’s wife and their two-year-old daughter were also on board). Many personal belongings, the ship’s log, and all of the cargo were also intact.
Since then, many theories have been put forward about the fate of the people on the Mary Celeste – from a pirate attack to a mutiny or insurance fraud – but the truth will likely never be known.
Image credits: commons.wikimedia.org
#15 Asia’s Disappearing WWII Shipwrecks
A recent article in The Guardian claims that there were approximately forty sunken World War II submarines in the Pacific Ocean, which were literally dismantled piece by piece by divers for personal use. The destroyed hulls of these submarines could contain up to 4,500 corpses of crew.
Image credits: Leonardo Lamas
#16 Mysterious Purple Blob On The Ocean Floor
Scientists from the E/V Nautilus team recently discovered a strange-looking purple blob while exploring the seafloor. After retrieving the strange object for further study, the scientists hypothesized that it was a previously unstudied nudibranch – a shell-less marine mollusc that simply crawls along the bottom in search of food. This mollusk does look pretty weird anyway!
Image credits: Brian Clark Howard
#17 El Dorado Of The Seas
On September 23, 1641, the English galleon Merchant Royal sank off the coast of Cornwall while returning to England with a cargo of gold and silver. Historians claim that, in addition to his own cargo, Captain John Limbrey also transferred goods from another damaged ship to his ship in the Spanish port of Cadiz.
However, excessive greed never leads to anything good. Off the English coast, the ship developed a major leak and sank with all its crew and treasure.
The legend of the Royal Merchant became a veritable El Dorado of the Seas, but over the following centuries, all attempts to find the sunken treasure have been unsuccessful. However, attempts continue to this day.
Image credits: Andreea Swank
#18 Deep Sea Hydrothermal Vents
In 1977, during a dive by the deep-sea submersible Alvin east of the Galapagos Islands, the first deep-sea hydrothermal vents were discovered. They are chimney-shaped formations on the ocean floor spewing water extremely rich in minerals, reaching temperatures of up to 750 degrees Fahrenheit.
Today, scientists have discovered that these vents are unique oases of life in the ocean depths, where sunlight doesn’t go. Moreover, according to recent research, the so-called “last universal common ancestor” – the hypothetical living organism from which all extant species descend – probably lived approximately 3.8 billion years ago near one of these vents.
Image credits: P. Rona / OAR/National Undersea Research Program (NURP); NOAA
#19 A UFO Crashed Off The Coast Of Shag Harbour, Nova Scotia
On October 4, 1967, just before midnight, eleven people in the small fishing village of Shag Harbor in Nova Scotia, Canada, reportedly witnessed a large, luminous object fly across the sky and disappear into the waters of the Gulf of Maine.
Numerous reports from local residents led to a massive rescue operation by police, but no wreckage or traces of the crash were actually found. The incident was widely covered in the Canadian press, but no further sensational news followed, and the public interest in the case gradually faded.
However, there is an unconfirmed story that a secret search operation was subsequently conducted in the region by Canadian and American military personnel.
Image credits: NLPEI
#20 Bioluminescent Waves And “Milky Seas”
Since ancient times, sailors have told us stories about the so-called “Milky Sea” – an eerie greenish glow in the ocean that appears very strange at night. This sparked more and more mystical stories until researchers finally found a rational explanation.
The glow is caused by bioluminescent bacteria living in the water, and the reasons why the ocean glows on some nights and not on others are linked to climate phenomena such as El Niño. Scientists continue to study this glow, hoping their research may shed new light on ocean ecology one day.
Image credits: Wanmei Liang, Story by Adam Voiland.
#21 The Loch Ness Monster
The Loch Ness Monster is perhaps the world’s most famous cryptozoological story – about a dinosaur supposedly living in Loch Ness in Scotland. The first reports of it are believed to date back to the 8th century AD, and it’s been a popular cultural icon since 1933, when a photograph of a long-necked creature swimming in the waters of the lake appeared.
Scientists believe it could’ve been a plesiosaur, a type of predatory aquatic dinosaur, had they not become extinct tens of millions of years ago. Some theories suggest that the lake was once connected to the ocean, assuming that millions of years ago a group of plesiosaurs may have entered the lake and survived the mass extinction of the dinosaurs.
Be that as it may, no reliable evidence has yet been obtained that any animals unknown to science actually live in the lake. But the lake became a wonderful tourist destination, and local residents actually earned tons of money by hosting tourists and selling souvenirs.
Image credits: Keystone
#22 The Sarah Joe Mystery
In February 1979, five Hawaiian fishermen set out to sea on a 17-foot Boston whaler named the Sarah Joe. Later, strong winds, turning into a gale, prompted relatives to attempt to signal from shore that it was time to return. However, the boat was not visible even from the nearest hill.
The boat never returned, and the five people on it were reported missing. However, the story took a new turn in 1988, when the wreckage of a boat later identified as the Sarah Joe was discovered on an uninhabited atoll near the Marshall Islands, 2000 miles from Maui.
A grave was also found, the remains of which turned out to belong to one of the missing fishermen, Scott Moorman. However, the mystery of how the boat ended up on the other side of the Pacific Ocean, what happened during those nine years, and the whereabouts of the other four remains unsolved.
Image credits: wirestock
#23 The Mystery Of Fishing Boat “Fausto”
In 1968, the fishing boat Fausto, carrying three crew members and one passenger, set sail from La Palma in the Canary Islands. Four days later, a British ship discovered the boat adrift in the ocean, far from land. The British offered to take the passengers on board, but they, even visibly exhausted, refused rescue, declaring they would continue on their own.
Four months later, Fausto was found floating in the ocean with only the mummified body of its passenger. Where the three crew members went, and what happened to the torn pages of the diary of that passenger, called Julio García, no one will ever know. Perhaps they had their own reasons for avoiding the scrutiny of prying eyes – but, as you understand, these are only conjectures.
Image credits: forums.spacebattles.com
#24 The Real Atlantis
Atlantis is a mythical ancient kingdom, the main source of information about which is the legendary philosopher Plato. According to him, Atlantis was an ancient superpower, but sank into the ocean as a result of a global catastrophe.
Since then, scientists have searched the bottom of both the Mediterranean Sea and the Atlantic Ocean beyond the Pillars of Hercules, uncovering numerous interesting archaeological finds, but Atlantis itself has never been found.
Today, it’s widely believed that the eruption of the Santorini volcano around 1610 BC, which brought an end to the Cretan-Minoan civilization, may have been the cause of Atlantis’s destruction. However, definitive confirmation of this theory remains pending.
Image credits: freepik
#25 Mystery Of The M.V. Joyita
In 1955, the former yacht “M.V. Joyita,” built a quarter century earlier for American film director Roland West and named after his wife, actress Jewel Carmen, was found drifting, half-submerged, in the Pacific Ocean.
By then, the vessel had ceased to be a luxury yacht and was on a routine voyage from Tokelau to Samoa. However, it never reached Samoa. None of the 25 passengers and crew were ever found.
Image credits: commons.wikimedia.org
#26 Mermaid Sightings Claimed In Israel
How can you profit from strange sightings? That’s right, turn it into a business! Many years ago, an urban legend arose in the Israeli city of Kiryat Yam that a mermaid lived in the local sea – at least several locals had seen one on the city beach.
City authorities approached this idea ingeniously – they established a reward for an authentic photograph of a mermaid, and later even erected a mermaid statue, turning it into a local landmark. The city budget received a great source of income, and tourists got a great place of interest.
Image credits: William Makepeace Thackeray (1811–1863) (not the actual photo)
#27 The Underwater “Pyramid” Near The Azores
In 2013, a gigantic underwater pyramid, nearly 200 feet tall, was discovered in the Atlantic Ocean near the islands of São Miguel and Terceira in the Azores. Given that the Azores are considered a possible location for the legendary Atlantis, the theory immediately arose that this pyramid was once human-made and towered over some ancient Atlantean city.
However, scientists, as always, are highly skeptical. According to them, it is simply the natural topography of the ocean floor, and its shape is simply due to underwater currents that have sculpted the volcanic rock over many millennia.
Image credits: Maahid Photos / pexels (not the actual photo)
#28 The Loneliest Whale In The World?
Since 1989, researchers began recording the songs of a strange whale – most likely a blue whale or fin whale – but in an unusual range: 52 hertz. Blue whales typically sing in the 15-20 hertz range, while fin whales sing at 20 hertz, so the “52-hertz whale” was immediately dubbed “the loneliest whale in the world” – simply because none of its fellow whales could actually hear it.
Interestingly, the whale’s recorded migration routes more closely resembled those of blue whales, but the timing of these movements mostly coincided with that of fin whales. In 1992, researchers noticed that the whale’s song had become slightly lower pitched, suggesting it had grown and matured.
The fact that the whale survived and reached adult size essentially means it was healthy. Moreover, in 2010, several other different signals in a similar range were recorded in the Pacific Ocean, so the “loneliest whale in the world” may actually have a group after all.
Image credits: Andrea Holien / pexels (not the actual photo)
#29 The Disappearance Of The SS Naronic
The SS Naronic was a ship of the White Star Shipping Company – yes, the same company that later launched the infamous SS Titanic. On February 11, 1893, the ship set sail on its final voyage from Liverpool to New York, but never reached American shores, vanishing without a trace with 74 people on board.
Later, reports emerged of letters in a bottle being found – supposedly from sailors of the crew, reporting a collision with an iceberg. Two empty lifeboats were also found, approximately in the same area where the SS Titanic would sink almost twenty years later.
However, the notes failed to withstand scrutiny, as the names of their authors didn’t match those of anyone on board. So the mystery of the ship’s disappearance still remains unsolved.
Image credits: commons.wikimedia.org
#30 Flannan Isle Mystery
In 1900, when relief crews arrived at the lighthouse on the remote island of Flannan in Scotland, they discovered the three previous keepers were nowhere to be found. The light had been out for several days, but everything inside the building looked as if something had caught the three men by surprise.
The beds were unmade, their outerwear was hanging in place – the official story is that all three were washed out to sea by a wave while attempting to secure equipment during a storm. What really happened is unlikely to be known.
Image credits: Paulius Dragunas
#31 Giant Oarfish
The oarfish is a rare and extremely long fish, rarely encountered by humans, living at big depths. Individual specimens can reach 30 feet, and scientists believe that many ancient legends about sea serpents actually originate from people seeing oarfish in the water.
Occasionally, oarfish get washed ashore before strong storms, so they have entered the folklore of coastal peoples as harbingers of some apocalyptic events. For example, on the eve of the catastrophic 2011 Tōhoku earthquake and subsequent tsunami, people also found numerous oarfish washed ashore.
Image credits: Wm. Leo Smith
#32 Vastly Under-Explored Deep Ocean
The world’s oceans cover approximately 70% of our planet’s surface, and let’s be honest, we haven’t even come close to exploring a fraction of the mysteries and living creatures the ocean conceals in its depths.
The estimated volume of the ocean that has been explored is about 20%, for which the bottom topography, water composition, and other data are roughly known. The rest is still an unexplored mystery, and it’s unknown when we’ll even come close to uncovering it.
Image credits: Ant Rozetsky
#33 “Milky Sea” Phenomenon
In 2019, the crew and passengers of the superyacht Ganesha became the first in human history to document the so-called “white ocean effect,” caused by colonies of bioluminescent bacteria that, instead of glowing blue or green, suddenly glowed white.
This effect, where a ship appears to float on an ocean of milk, was described by ancient sailors – however, photographs and videos of this unique phenomenon were only captured a few years ago. Scientists, incidentally, are still debating what exactly causes the bacteria to glow in such an unusual way.
Image credits: Jess Thomson
#34 The Bloop
In 1997, National Oceanic and Atmospheric Administration (NOAA) researchers recorded a strange, high-amplitude, ultra-low-frequency underwater sound at a remote location in the South Pacific Ocean. The sound was nicknamed “The Bloop.”
There have been numerous theories about the sound’s origin, ranging from that it emanated from some large marine animal (later disproved) to tectonic shifts. Today, scientists believe it is simply the sound caused by the disintegration and movement of large ice masses, such as icebergs.
However, there still remains the possibility that it is simply the sound emitted by Cthulhu, sleeping on the seafloor, (but this is uncertain…)
Image credits: National Oceanic and Atmospheric Administration
#35 The Disappearance Of The SS Waratah
The SS Waratah was a cargo-passenger liner en route from Australia to London that vanished without any trace in the ocean between Cape Town and Durban in 1909, taking with it 211 passengers and crew. A lengthy search yielded no results, although several strange pieces of debris washed ashore several months later, which could have been fragments of the SS Waratah.
Most likely, the ship simply encountered a severe storm raging at the time, capsized, and sank – at least some passengers reported a tendency for the ship to list to starboard. One of them, engineer Claude Sawyer, even disembarked, canceling his previously booked passage to England. In doing so, Sawyer actually saved his own life.
Many years later, former military officer Edward Joe Conquer recounted that while watching the sea from the shore through a telescope that day, he saw a steamship engulfed by a huge wave. But whether it was the SS Waratah, and how true these reports were, no one ever knew.
Incidentally, since then, there have been reports of eight ships of various types also bearing the name Waratah that sank in shipwrecks. However, the steam tug ST Waratah, built in 1902, is still operational in on of the Australian ports.
Image credits: Unknown author
#36 Mysterious Disappearance Of Ghost Ship Carroll A. Deering’s Crew
In January 1921, another mysterious disappearance of crew and passengers – 12 in all – befell the schooner Carroll A. Deering, en route from Barbados to Norfolk, Virginia.
The ship was found off the coast of North Carolina, its cargo and the crew’s personal belongings intact, but completely deserted. The fate of the twelve crew members still remains unknown.
Image credits: commons.wikimedia.org
#37 The Sinking Of MV Derbyshire
In September 1980, the British bulk carrier MV Derbyshire was caught in a typhoon off the coast of Japan and sank, taking the lives of 44 crew members with it. Fourteen years later, the wreckage was finally found at the ocean floor, and a detailed investigation into the disaster began.
Today, we know roughly how it all happened. Waves crashing over the ship’s bow tore off the covers of small ventilation pipes on the bow, which had been flooding the ship for several days, gradually causing the bow to sink.
Then, when particularly strong waves struck the ship, the force of the water already inside ripped off several hatches in the cargo hold, and the bulk carrier sank within minutes.
Image credits: PA Images / Getty Image
#38 The Upsweep
“The Upsweep” is the name given to a sound recorded by the National Oceanic and Atmospheric Administration’s (NOAA) Equatorial Autonomous Hydrophone Arrays. The sound was recorded in August 1991 by the Pacific Marine Environmental Laboratory’s (PMEL) SOSUS underwater sound system and was loud enough to be heard throughout the whole Pacific Ocean.
The sound was initially thought to be biological in origin, but this theory was officially dismissed in 1996. The source of the sound is located in a remote location in the Pacific Ocean, roughly between New Zealand and South America. The sound typically peaks in spring and fall and consists of a long sequence of repeating vertical “sweeps” from low to high frequency, each lasting around three seconds.
The sound has been gradually decreasing in volume recently, but it can still be heard. Scientists currently believe the sound is of volcanic origin, but definitive confirmation of this theory is still lacking.
Image credits: pmel.noaa.gov