Unanswered Questions Of The Ocean

The ocean covers most of our planet, yet much of it remains unexplored. Beneath the surface lie baffling mysteries that continue to puzzle scientists and explorers. Strange events, unusual creatures, and unexplained phenomena raise more questions than answers. If you’re curious about those secrets, here are 20 ocean mysteries waiting to be solved—read on to uncover what continues to intrigue people all over the world.

Charles J. Sharp on Wikimedia

1. The Baltic Sea Structure

Discovered in 2011, sonar scans revealed a bizarre, disc-shaped structure on the Baltic Sea floor. Some claim it resembles a crashed spacecraft, while others suggest it’s a natural rock formation. Its unusual shape, strange electromagnetic interference, and lack of full exploration keep its origins hotly debated.

The Case Of The Baltic Sea Anomaly | The Mystery Beneath by Timeline - World History Documentaries

2. The Immortal Jellyfish

The jellyfish Turritopsis dohrnii defies aging by reverting to its juvenile stage. This means it could theoretically live forever. Scientists don’t have answers for how it escapes predators or spreads across oceans, which leaves this tiny survivor one of nature’s strangest mysteries.

Conny on Wikimedia

3. The Disappearance Of The Mary Celeste

In 1872, sailors found the Mary Celeste drifting in the Atlantic with no crew aboard. The ship showed no sign of struggle, storm damage, or piracy. Bodies or wreckage never appeared, and the sea has kept the mystery locked ever since.

Unconfirmed, possibly Honore Pellegrin (1800–c.1870). This speculative attribution is suggested in Paul Begg: Mary Celeste: The Greatest Mystery of the Sea. Longmans Education Ltd, Harlow (UK) 2007. Plate 2 on Wikimedia

4. The Yonaguni Monument’s Purpose

Beneath Japan’s waters lies the Yonaguni Monument, a massive structure some believe is a 10,000-year-old ruin. Others argue it formed naturally through shifting geology. No artifacts or inscriptions exist, and its terraces remain an unanswered underwater puzzle.

Vincent Lou from Shanghai, China on Wikimedia

5. The Origin Of The Dragon’s Triangle

Off Japan’s coast sits the Dragon’s Triangle, a stretch of sea where ships and planes vanish. Theories include underwater volcanoes or strange magnetic forces, but with no proof. Its reputation rivals the Bermuda Triangle, so it remains one of the Pacific’s most puzzling danger zones.

Artanisen on Wikimedia

6. The Migration Of Monarch Eels

European eels pull off one of nature’s greatest mysteries. They leave Europe, disappear into the Atlantic, and somehow reach the Sargasso Sea to spawn. No one has ever witnessed the event. Even stranger, their larvae—called leptocephali—look like tiny willow leaves drifting in the ocean.

Ffish.asia on Wikimedia

7. The Mariana Trench’s Unexplored Depths

The Mariana Trench drops deeper than any place on Earth. Scientists have only mapped a sliver of it—about 5%. Pressure over a thousand times greater than sea level makes it nearly impossible to explore. To picture its size, Mount Everest would vanish inside easily.

astrobob on Wikimedia

8. The Fate Of The SS Waratah

In 1909, the SS Waratah vanished off South Africa with 211 people on board. Not a single piece of wreckage surfaced. Blame is mostly put on rogue waves or sudden storms. Strangely, this “unsinkable” ship earned its reputation just before it disappeared forever.

Unknown authorUnknown author on Wikimedia

9. The Cause Of The Agulhas Current’s Shipwrecks

Sailors call the Agulhas Current the “graveyard of ships” for a reason. Powerful waters crash into fierce winds and waves to create chaos no one can predict. Over centuries, countless wrecks have sunk beneath the surface.

NASA/METI/AIST/Japan Space Systems, and U.S./Japan ASTER Science Team on Wikimedia

10. The Disappearance Of The Flannan Isles Keepers

In 1900, three men vanished from a lonely lighthouse on the Flannan Isles. Theories range from massive waves to brutal storms. However, zero traces were found. The lighthouse clock had stopped at midnight, making the mystery more chilling.

Chris Downer on Wikimedia

11. The Deep-Sea Snow

Imagine flakes falling through total darkness—only this snow is made of organic debris. Marine snow feeds entire ecosystems in the deep, and scientists know it helps with the carbon cycle. Yet, its patterns remain unpredictable. 

NOAA National Ocean Service on Wikimedia

12. The Cause Of Mass Strandings Of Whales

Whale strandings remain one of the ocean’s great mysteries. Entire pods beach themselves, but no single cause explains it. It could be realtor to sonar interference, disease, or disorientation. In New Zealand, locals once saved more than 30 pilot whales by using sheets to refloat the animals.

Bahnfrend on Wikimedia

13. The Purpose Of Whale Songs

Humpback whales sing like ocean poets, filling the water with complex melodies. No one can say for sure why. Some think the songs attract mates, others believe they help whales find their way. What’s certain is that these calls travel astonishing distances underwater.

Christopher Michel on Wikimedia

14. The Location Of San José’s Sunken Treasure

The San José, a Spanish galleon sunk in 1708, is said to hide a fortune in Caribbean waters. Its exact location sparks dispute, while deep-sea conditions and legal fights stall recovery. Experts even estimate its treasure could be worth an unbelievable $20 billion today.

Samuel Scott on Wikimedia

15. The Deep-Sea Coral Cities

Far below the surface, massive coral structures rise like hidden cities. Scientists still puzzle over how they support life without sunlight or how their ecosystems function. These corals are ancient beyond belief—older than the pyramids themselves, with ages stretching back more than 4,000 years.

NOAA Office of Ocean Exploration and Research, Deep-Sea Symphony: Exploring the Musicians Seamounts on Wikimedia

16. The Behavior Of Dumbo Octopus

A dumbo octopus glides through the deep with fins shaped like ears, which earn it this charming name. Despite its popularity, almost nothing is known about how it feeds, reproduces, or survives at extreme depths. The creature’s secret life continues to fascinate scientists around the world.

NOAA Ocean Exploration & Research from USA on Wikimedia

17. The Phenomenon Of Rogue Waves

Once dismissed as sailor myths, rogue waves—massive walls of water appearing without warning—are now proven by science. Yet, no one fully understands how they form. Satellites show they can rise taller than skyscrapers, swallowing ships in moments, leaving researchers scrambling for answers.

NOAA on Wikimedia

18. The Vampire Squid’s Light Displays

Deep in the ocean, the vampire squid dazzles with sudden bursts of bioluminescence. Scientists still debate whether the flashes scare predators or attract mates. What’s even stranger? It can release glowing mucus to light up the dark like underwater fireworks.

This illustration was made by Citron You must credit this : Citron / CC-BY-SA-3.0 on Wikimedia

19. The Oceanic Nitrous Oxide Surges

At times, the ocean releases sudden bursts of nitrous oxide, and researchers don’t have a clear explanation for that. They believe that deep-sea microbes may be involved, but the process remains uncertain nonetheless. Interestingly, this "laughing gas" traps heat 300 times more fiercely than carbon dioxide.

Ljeto on Wikimedia

20. The Origin Of The Bimini Road

Off the Bahamas lies the Bimini Road, a mysterious line of stones that looks like a roadway beneath the sea. Some claim it’s an ancient man-made structure, while others insist it’s natural. Despite dives and studies, no evidence has ever confirmed its age or origin.

Original picture by NASA on Wikimedia