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 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.
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.
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25points
#2 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.
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.
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25points
#3 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.
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.
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23points
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 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.
"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.
23points
#5 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.
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.
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21points
#6 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.
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.
21points
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 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.
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.
20points
#8 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.
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.
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20points
#9 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.
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.
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19points
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 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.
Each submarine accident had its own unique details, and many of them remain a mystery to this day.
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19points
#11 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.
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.
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19points
#12 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.
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.
19points
#13 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.
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.
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18points
#14 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.
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.
ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Center., NASA/JSC
Report18points
#15 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.
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.
18points
#16 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.
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.
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18points
#17 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.
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.
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18points
#18 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.
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.
17points
#19 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.
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.
17points
#20 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.
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17points