The Most Dangerous Ocean Expeditions Ever Attempted

The ocean accounts for over 70% of our planet, yet we have more information about the surface of Mars than we do about its depths. Lead a group of brave explorers, venturing into the wilds and delving below the waves to seek out nature’s greatest prize. Some were in pursuit of scientific enlightenment, others had moved to seek their fortune or adventure and many would never return home. These are the tales of the most dangerous sea voyages ever undertaken – expeditions that tested human bravery and determination to impossibly extreme limits.

Why Exploring the Ocean Is So Deadly

But before we take a deeper dive into individual journeys, let’s understand why the ocean is one of the most hostile environments on Earth. In contrast to space exploration, where friends inhabit the void, ocean explorers are meddled with by crushing pressure, freezing temperatures and total darkness. At depths greater than 1,000 meters, the pressure is intense enough to crush metal cans of soda. Throw in the unreliability of storms, of equipment and wear and tear on gigantic slick-sided boxes encased by millions of gallons of water, and it’s recipe for disaster.

Early explorers were even worse off. Lacking modern technology, they wore wooden boats and simple navvies; then it was little more than shoe leather. Make one wrong move, and you might drown, starve or become lost forever in the endless blue wilderness.

The Franklin Expedition: Frozen in Time

In May 1845, Sir John Franklin set sail from England with a crew of 129 men on two ships, HMS Erebus and HMS Terror, intent on navigating the Northwest Passage — a route through the Arctic Ocean that connects the Atlantic to the Pacific. This was not just any voyage — it was supposed to be Britain’s finest hour in polar exploration. The boats actually were state-of-the-art for the time, featuring steam engines and ice-breaking reinforced hulls.

They were not seen alive again.

The reason the expedition had been so dangerous was because of the unforgiving nature of the Arctic. The ships became locked in thick ice off King William Island in September 1846. Months passed, and years, and supplies dwindled. The men were met with temperatures that could freeze exposed skin in minutes. After Franklin’s death in June of 1847, the surviving crewmembers left the ships in April 1848, hoping to walk hundreds of miles to get out.

None survived. Search parties turned up proof of desperate conditions — equipment abandoned, bones scattered and evidence of cannibalism. The wrecks of both ships were not found until 2014 and 2016, over one hundred seventy years after they vanished. The Franklin Expedition is a chilling reminder of how swiftly the ocean can become treacherous, even for prepared and seasoned explorers.

To the Bottom of the World: The Mariana Trench Dives

Consider diving nearly seven miles below the ocean surface, in condition of pressure akin to what you would experience if 50 jumbo jets were piled on top of you. That’s precisely the challenge faced by explorers trying to descend to the bottom of the Mariana Trench, the lowest point on Earth.

The first successful descent came on Jan. 23, 1960, when Jacques Piccard and Don Walsh huddled into a cramped submersible named the Trieste. It was a nearly five-hour descent through absolute darkness in the water. One misstep, one hole in the shell and they belonged to the ages. Roughly 30,000 feet below them they heard a loud crack — here had been a tiny leak in the window. But they pressed on.

At 35,814 feet beneath the surface, they touched down in the Challenger Deep, which is the lowest known point in Earth’s oceans. They remained at the bottom for just 20 minutes before starting their ascent. The pressure was so great that the sphere in which they sat was just seven feet in diameter — roughly the dimensions of a small closet.

Filmmaker James Cameron achieved the same thing in 2012, spending three hours and 20 minutes in the trench. His submersible was equipped with high-tech cameras and robot arms, but the risk remained very real. He was forced to call the mission short because of a leak in his hydraulic fluid. The crushing cold at the bottom of the ocean is not impressed by modern technology.

Table: Comparing the Depths of Well-Known Ocean Dives

From the Raft: The Story of Thor Heyerdahl and His Crew of Five Men on a Jaw-Dropping 7000-mile, Unpaced Voyage Across the Pacific!

In 1947, the Norwegian explorer Thor Heyerdahl proposed a crazy-sounding theory: ancient South Americans could have settled Polynesia by voyaging across the Pacific Ocean on primitive rafts. Scientists laughed at him. So he set out to prove them wrong by doing that piece of it himself.

Heyerdahl and five fellow adventurers constructed a raft out of balsa wood logs, the Kon-Tiki, launching from Peru on April 28, 1947. There was no engine, no modern navigation equipment, and nothing to steer with but a primitive rudder. Their destination lay 4,300 miles across open ocean.

The dangers were constant. Enormous waves broke over the raft each day. Sharks misted around them, occasionally skimming the side of the logs. Equipment broke repeatedly. They ate fish they caught and drank the rainwater they collected. At night, the crew alternated staying up to keep a watch for treacherous weather or shipping traffic.

One hundred and one days after putting out to sea, the raft crashed into a reef in the Tuamotu Islands. All six men survived, and the voyage was theoretically feasible. Modern archaeologists have called into question Heyerdahl’s theory about Polynesian settlement; no one questions, however, the courage it took to venture across thousands of miles of ocean in a wooden raft bound together with rope.

Solo Circumnavigation: Alone Against the Sea

To sail solo around the world is to confront every ocean peril on your own. No one there to help if you fall ill. No one to stand at the wheel in storms. No backstop when the equipment breaks down. You are all alone with the sea.

In 1968, the Sunday Times Golden Globe Race dared sailors to race single-handedly around the world without stopping. Nine men started. Only one finished.

Robin Knox-Johnston became the first man to sail solo nonstop around the world with his 312-day circumnavigation. But the race’s most tragic character was Donald Crowhurst. Faced with financial ruin if he didn’t get to the end of the race, Crowhurst falsified his position reports and sailed in circles in the Atlantic. The weight of guilt seems to have got the better of him — he vanished from his boat in July 1969, thought to have thrown himself overboard.

The Frenchman Bernard Moitessier was winning the race when he made an incredible decision: Instead of ending it, he sailed on. He had learned to love the seafaring life and could not bear to return to civilization. After 301 days, he finally made it to Tahiti via a journey and a half around the world.

Those solo voyages are still incredibly perilous. Contemporary sailors still grapple with waves in excess of 50 feet, icebergs, equipment breakdowns and (my personal downfall) fatigue that can lead to gelid screw-ups.

Shackleton’s Endurance: Survival in Antarctica

The 1914 Imperial Trans-Antarctic Expedition of Ernest Shackleton did not proceed as anticipated. His ship, Endurance, became stuck in Antarctic ice and was eventually crushed and sunk. But what came next would end up being one of the greatest survival stories in history.

Shackleton and his 27-man crew floated on ice floes for months. When the ice’s grip loosened, they put three small lifeboats in water and journeyed through perilous, iceberg-laden seas to desolate Elephant Island. But they couldn’t last there long.

Shackleton then made a decision that can best be described as batshit crazy: He would sail one of the small boats 800 miles across the Southern Ocean to South Georgia Island for help. He set out in the James Caird, a tiny boat just 22 feet long, with five men.

They fought their way across the world’s deadliest ocean for 17 days. Waves reached 60 feet high. Freezing spray coated the boat with ice, and it threatened to smash them over. They steered by primitive instruments, often unable to see the sun so they could fix their positions. Somehow, they made it.

But they’d landed on the wrong side of South Georgia. Shackleton and two men later hiked for 36 hours without stopping, traversing the mountainous island to a whaling station. Three months later, he came back to rescue the men on Elephant Island. Amazingly, all 28 men lived to tell the tale.

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The Voyage of the Bounty Launch: The True Story of an Open Boat Journey Round the World After the Mutiny on the Bounty

So as the story goes (as told so famously in “Mutiny on the Bounty”), following a famous act of mutiny aboard H.M.S. Bounty in 1789, Capt. William Bligh and 18 loyal sailors were sent out to sea in a 23-foot open boat with only dough for bread, water and some rum from what were then known as the Friendly Islands. They had little food, not much water and were thousands of miles from anywhere safe.

What came next was a navigational epic and an endurance event for the ages. Bligh and his men travelled 3,618 nautical miles to Kupang in Timor, where Bligh engaged a Dutch official to acquire assistance for the men; it took 47 days. Reefs and unfriendly islands lurked in the dangerous waters through which they made their way. Food ran out. Water was limited to a few ounces a day. Men contracted saltwater sores from their exposure to the water.

Despite the conditions, Bligh made meticulous entries and maintained accurate navigation records. During the voyage, only one man, murdered by island natives while they stopped to pick up provisions on an island, died. The survivors all endured the type of trip that should never have been possible.

Bligh’s accomplishment has since been studied in maritime schools as a demonstration of extraordinary seamanship under the most adverse conditions.

Modern Perils: The Deepwater Horizon Link

Exploring the ocean isn’t all about wooden ships and historical voyages. Contemporary expeditions encounter dangers that are different but every bit as deadly. The Deepwater Horizon disaster in 2010 was an indication of just how perilous work in the ocean can be.

The drilling rig was working in 5,000 feet of water when a blowout ensued and a subsequent explosion killed 11 workers — generating the biggest marine oil spill in history. The rig remained ablaze for two days before it sank. The oil continued to gush for nearly three months, dumping millions of barrels of crude oil into the Gulf of Mexico.

The failure brought to light the dangers of deep-ocean work. At those depths, pressure magnifies everything that is dangerous. The equipment fails in ways the engineers didn’t predict. Response times are slower. The margin for error disappears.

Chart: Deaths on Major Ocean Expeditions, by Century

The Hunt for MH370: A Search in Vain?

The disappearance of Malaysia Airlines Flight 370 in 2014 set off what would become one of the largest and most risky ocean search operations ever. The plane disappeared somewhere in the Indian Ocean, one of the most isolated and brutal marine environments on earth.

Search teams faced incredible challenges. The ocean bottom in the search area is 12,000 to 20,000 feet deep and is marked by mountains, valleys and volcanic ridges. Drones and underwater vehicles fought powerful currents that could potentially wash them off course. Millions of dollars in equipment were lost. Vessels sailed thousands of miles from a port and confronted awful weather, mechanical failures.

Three years and $150 million later, after scouring 46,000 square miles of ocean floor in its main search, the operation was called off in 2017. Private searches went on, but turned up nothing. A few scattered bits washed up on distant shores, but the primary wreckage remains missing. The 200-ton aircraft with 239 souls on board: swallowed by the Indian Ocean, and we could not find it.

Free-Diving Records: Pushing Human Limits

Free-diving, or diving deep on one breath without equipment, might just be the purest and most dangerous form of ocean exploration. Divers plummet hundreds of feet underwater without a tank, battling against the clock as their oxygen-starved bodies scream for air.

The men’s no-limits free-diving record now stands at 702 feet, set by Herbert Nitsch in 2007. The women’s record is 525 feet by Tanya Streeter. Below that depth, pressure collapses the lungs to roughly the size of oranges. The heart rate slows dramatically. Those can cause blood vessels in the eyes to burst. And for divers, there’s nitrogen narcosis, giving them a drunk-like state that affects judgment.

The sport has claimed the lives of many divers. Nicholas Mevoli, who died in 2013 after a dive to 236 feet. He rose, flashed the okay sign and then lost consciousness and never regained it. Her air bag failed to inflate properly for the ascent, and Audrey Mestre died in 2002 during a record attempt.

Free-divers say that the experience of diving so deep in a single breath induces a meditative state unlike any other. But one error, one instant of panic, and they slip under before anyone can assist.

Facing the Perfect Storm

Andrea Gail fishing boat sailed from Gloucester, Mass., in September 1991, seeking a swordfishing catch. Captain Billy Tyne and his five crew members were never seen again. They ran into what meteorologists refer to as a “perfect storm” — pure weather systems uniting and together assaulting superstorm with waves of 100 foot and winds in excess of 70 mph.

The boat’s final transmission was on October 28. After that, silence. The storm was so massive and the seas so violent that the boat likely foundered quickly, with the crew having no time to send out a distress call. Only a small amount of debris was ever found. No bodies were found.

The disaster, which was immortalized in Sebastian Junger’s book and movie of the same name, underscored the inherent danger that commercial fishermen are forced to accept. Despite the tools of modern weather forecasting and communication, the ocean can still deliver conditions no ship can withstand.

Why People Still Do It

With all that can go wrong, why venture anywhere near the ocean? Answers differ, but a few themes crop up again and again:

Scientific discovery drives many expeditions. Marine biologists believe we have explored 5% of the world’s oceans at best. New species are discovered regularly. Knowing how ocean currents, temperature shifts, ecosystems and other aquatic systems work is essential to predict climate change and protect the planet.

Solo sailors and adventurers are motivated by personal challenge. They want to test themselves against the most powerful force in nature. To finish a demanding ocean crossing is to prove something to themselves and the world.

Dwindling economic opportunity forces commercial fishermen into harm’s way. The hunger for seafood leaves fishing boats working in conditions that would frighten most people.

Search expeditions are still being lured by historical mysteries. The ocean is full of lost ships, ancient cities and disappeared airplanes. The need to find these answers supersedes the dangers present.

Frequently Asked Questions

What makes the ocean a more threatening place than other environments?

The sea congregates several perils in one place. Crushing pressure at those depths is enough to implode submarines and human bodies. In minutes, cold water is pushing us into hypothermia, as it shuts down critical body organs. The size has the effect of putting help far away, and bad weather can keep rescue teams at bay for days. Mountains and deserts may offer shelter at times, but the ocean has no place to hide from storms or mechanical failure.

Is technology making sailing and ocean exploration safer?

Technology has certainly helped, but the ocean is still incredibly treacherous. Navigation equipment, weather forecasting and communication of modern ships are clearly superior. Subs are built to handle pressure with advanced materials. But technology also enables us to go deeper, and farther away from home than before – and that creates new dangers. Equipment can malfunction anyway, and at great depths rescue is often out of the question.

Which was the deadliest single oceanic journey?

There are so many disasters that might not have been well documented, and it’s difficult to choose just one expedition. But the defeat of the Spanish Armada in 1588 saw an estimated 15,000 to 20,000 sailors die during storms on their way back from fleeing England. For sheer exploratory slaughter, the loss of 129 men on the Franklin Expedition is one of the worst single-expedition death tolls.

Do people still try sailing across oceans on their own today?

Yes, and audiences can’t get enough of them. On the French side, events such as the Vendée Globe race bring dozens of solo sailors who race around the world without stopping. Vodislav’s crossing follows a number this year and last, all of them well equipped with modern technology such as satellite phones and GPS to ward off the ills that plagued sailors in years gone by. Solo sailing can be very tough and demanding, both physically and mentally.

How deep has anyone ever gone in the ocean?

When Victor Vescovo in 2019 descended 35,853 feet into the Mariana Trench, it was a bit further than Trieste got to in 1960. This is still the deepest point human beings have ever gone to. At this depth, the pressure is more than 1,000 times what we feel at sea level — it’s powerful enough to crush nearly anything.

What steps do today’s explorers take in order to set off on hazardous ocean voyages?

It requires preparation lasting months or years — training, equipment testing and backup planning. Sailors like the men in question, who spend years learning how to navigate and repair a ship. Pilots of submersibles are extensively trained in pressure chambers and simulators. Expedition kits contain backup systems for vital gear. Medical training is a must in part because professional help can be days out. For all that preparation, however, the ocean still shocks people with its hidden dangers.

Lessons Written in Salt Water

There is something valuable to be learned from every treacherous journey upon the sea. The Franklin Expedition demonstrated the value of flexibility and preparedness. Shackleton’s survival demonstrated that leadership and morale were as important as equipment. The Deepwater Horizon disaster showed that even with all our technology, we still don’t know much about the depths of the ocean.

These tales are a reminder that the ocean is still wild and untamed. We have built cities, subdued rivers and scaled the highest mountains. But the sea has no respect for human accomplishment. There, it follows its own rules, creates its own weather and keeps its secrets buried under miles of dark water.

The kind of explorers who embark on crazy oceanographic missions are not fools, they’re curious, and they possess that peculiar human impulse to keep testing the limits. Others want to use their understanding of science to help all humanity. Still others match themselves against the ultimate adversary. But many others are pulled to the sea in ways they cannot fully articulate.

As technology advances, we will explore ever deeper and more distant ocean territory. With new discoveries come new hazards. The next generation of explorers of the ocean will have problems that we can’t even conceive at this point. But if history is any guide, bold individuals will always attempt the inconceivable — setting sail into uncharted territory and plunging themselves into darkness.

Thousands have been lost in the ocean over time. It has wrecked ships, imploded submarines and devoured entire expeditions with hardly a trace. But it is also home to wonders beyond our wildest imagination — creatures that glow in the dark, mountains taller than Everest and ecosystems we are only just beginning to understand.

These perilous commutes are more than heartbreaking narratives. They are testament to the courage, determination and endless curiosity of humanity to explore unknown worlds. Every expedition, whether it’s successful or not, contributes to our understanding and inspires the next generation of explorers. The sea may be treacherous, but it still beckons to those bold enough to respond. And as long as mysteries lurk beneath the waves, adventurers will continue seeking to do the impossible, risking it all—just to explore.