Editor’s note: Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more.
The submersible vehicle that was lost at sea is part of a relatively new effort enabling tourists and other paying customers to explore the depths of the ocean, the vast majority of which has never been seen by human eyes.
Though people have been exploring the ocean’s surface for tens of thousands of years, only about 20% of the seafloor has been mapped, according to 2022 figures from the National Oceanic and Atmospheric Administration.
Researchers often say that traveling to space is easier than plunging to the bottom of the ocean. While 12 astronauts have spent a collective total of 300 hours on the lunar surface, only three people have spent around three hours exploring Challenger Deep, the deepest known point of Earth’s seabed, according to the Woods Hole Oceanographic Institution.
In fact, “we have better maps of the moon and Mars than we do of our own planet,” said Dr. Gene Feldman, an oceanographer emeritus at NASA who spent more than 30 years at the space agency.
There’s a reason deep-sea exploration by humans has been so limited: Traveling to the ocean’s depths means entering a realm with enormous levels of pressure the farther you descend — a high-risk endeavor. The environment is dark with almost no visibility. The cold temperatures are extreme.
The submersible, which is believed to have been destroyed in a catastrophic implosion, killing all five people aboard, was en route to explore the wreckage of the RMS Titanic. The remnants of the ship lie about 900 miles (1,450 kilometers) off the coast of Cape Cod, Massachusetts, and about 12,500 feet (3,800 meters) underwater. Operated by OceanGate Expeditions, a private company based in Washington state, the tourist vessel lost contact with its mother ship after departing on Sunday.
The US Navy later revealed that it had detected a sound on Sunday that would match an implosion, indicating the vessel, called the Titan, was rapidly destroyed. The disaster could have occurred during the submersible’s descent, as pressure on the vehicle grew.
Many of the factors that made the multiday search for the vessel so difficult are also the reasons a comprehensive exploration of the ocean floor remains elusive.
“Aquatic search is pretty tricky, as the ocean floor is a lot more rugged than on land,” said Dr. Jamie Pringle, a reader in forensic geoscience at England’s Keele University,in a statement.
In the days before the submersible’s likely implosion was confirmed, search and rescue teams relied on sonar, a technique that uses sound waves to explore the opaque depths of the ocean, to attempt to pinpoint the vehicle in case it had been stranded on the seafloor. The challenging process requires a very narrow beam with a high frequency to offer a clear picture of where objects might be.
A history of ocean exploration
The first submarine was built by Dutch engineer Cornelis Drebbel in 1620, but it stuck to shallow waters. It would take nearly 300 years — in the aftermath of the Titanic disaster — before sonar technology began to offer scientists a clearer picture of what lies in the ocean’s depths.
A major step forward in human exploration came in 1960 with the historic dive of the Trieste bathyscaphe, a type of free-diving submersible, to the Challenger Deep, located more than 35,800 feet (10,916 meters) underwater.
Explorer and physicist Auguste Piccard is seen wearing a life jacket as he emerges from the bathyscaphe Trieste, which he designed, after making a world record dive of 10,335 feet (3,150 meters) on October 3, 1953. The dive was made off the west coast of Italy.
Only a few missions since have returned to such depths. And the trips are extremely dangerous, Feldman said.
For every 33 feet (10 meters) traveled beneath the ocean’s surface, the pressure increases by one atmosphere, according to NOAA. An atmosphere is a unit of measure that’s 14.7 pounds per square inch. That means a trip to the Challenger Deep can put a vessel under pressure that is “equivalent to 50 jumbo jets,” Feldman noted.
At high pressure, the tiniest structural defect can spell disaster, Feldman added.
During the 1960 dive of the Trieste, passengers Jacques Piccard and Don Walsh said they were stunned to see living creatures.
“Right away, all of our preconceptions about the ocean were blown out the window,” Feldman said.
What lies at the bottom of the ocean
While what’s considered the deep ocean extends from 3,280 feet to 19,685 feet (1,000 meters to 6,000 meters) beneath the surface, deep-sea trenches can plunge to 36,000 feet (11,000 meters), according to the Woods Hole Oceanographic Institution in Massachusetts. This region, called the hadal or hadalpelagic zone, is named for Hades, the Greek god of the underworld. In the hadal zone, the temperatures are just above freezing, and no light from the sun penetrates.
Scientists were first able to prove that life existed below 19,685 feet in 1948, according to the institution.
Discoveries at the Challenger Deep have been remarkable, including “vibrantly colorful” rocky outcrops that could be chemical deposits, prawnlike supergiant amphopods, and bottom-dwelling Holothurians, or sea cucumbers.
Feldman also remembers his own attempt in the 1990s to catch a glimpse of the evasive giant squid, which lurks in the inky depths of the ocean. The first video of a live creature, which can grow to nearly 60 feet (18 meters) long, was captured in the deep sea near Japan in 2012, according to NOAA.
A new world also opened in the 1970s, Feldman said, when “an entirely alien ecosystem” was discovered by marine geologist Robert Ballard, then with the Woods Hole Oceanographic Institution, within the sea near the Galápagos Rift — “with these giant worms, giant clams, and crabs and things that lived at these … vents under the sea.”
A female deep-sea anglerfish attracts prey with a lure projecting from her head in the Atlantic Ocean.
The unusual creatures — some of which glow with bioluminescence to communicate, lure prey and attract mates — have carved out habitats within the steep walls of ocean trenches. These life forms have adapted to live in the extreme environment and don’t exist anywhere else on the planet. Instead of relying on sunlight for fundamental processes, they use chemical energy belched out from hydrothermal seeps and vents formed by magma rising from beneath the ocean floor.
The chilly seawater seeps through seafloor cracks and becomes heated to 750 degrees Fahrenheit (400 degrees Celsius) as it interacts with the magma-heated rocks. The chemical reactions produce minerals containing sulfur and iron, and the vents spew out the nutrient-rich water that supports the ecosystem of unusual marine life clustered around them.
Researchers have used the submersible Alvin to discover strange sea life, study plate tectonics and hydrothermal vents — and to explore the Titanic in 1986 after Ballard located the famed shipwreck.
Researchers from the WHOI and NASA have collaborated to develop uncrewed autonomous underwater vehicles that can descend through the tricky terrain of the trenches and withstand pressures greater than 1,000 times that at the ocean’s surface. The vehicles can investigate the diversity of life within the trenches, and they could also help scientists explore oceans on the moons around Jupiter and Saturn in the future.
A giant isopod is a deep-sea crustacean.
Why mapping the ocean is so challenging
From a strictly scientific perspective, touristic trips to the ocean floor do little to advance our understanding of the ocean’s mysteries.
“Humans like superlatives,” Feldman said. “We want to go to the highest, the lowest, the longest.”
But only a “very small percentage of the deep ocean, and even the middle ocean, has been seen by human eyes — an infinitesimal amount. And a very, very small amount of the ocean floor has been mapped,” he added.
The reason, Feldman noted, largely comes down to cost. Boats equipped with sonar technology can rack up exorbitant expenses. Fuel alone cantotal up to $40,000 per day, Feldman said.
There is, however, currently an effort underway to create a definitive map of the ocean floor, called Seabed 2030.
Still, there are huge gaps in what’s known of the deep sea. Of the 2.2 million species believed to exist in Earth’s oceans, only 240,000 have been described by scientists, according to the Ocean Census, an initiative to record and discover marine life.
However, it’s impossible to know for certain just how many sea creatures exist, Feldman noted.
Most of the seafloor explored during Dive 07 of the 2019 Southeastern US Deep-sea Exploration, conducted by NOAA and its partners, was covered with these manganese nodules, the subject of the Deep Sea Ventures pilot test nearly five decades ago.
“We can make estimates all the time but then … you go somewhere new and discover an entirely new genus or an entirely new way of living,” he said.
Advances in technology may make human exploration of the ocean depths unnecessary. Innovations such as deep-sea robots, high-resolution underwater imaging, machine learning, and sequencing of DNA contained in seawater will help accelerate the speed and scale of discovery of new life forms.
“We have better maps of the moon’s surface than of the seafloor because seawater is opaque to radar and other methods we use to map land,” said marine ecologist Alex Rogers, a professor of conservation biology at the University of Oxford in the United Kingdom. “However, 150 years of modern oceanography have led to better understanding of many aspects of the ocean such as the life it contains, its chemistry and its role in the Earth system.”
Mapping the ocean “helps us to understand how the shape of the seafloor affects ocean currents, and where marine life occurs,” Rogers added. “It also helps us to understand seismic hazards. So it is basic fundamental science of overwhelming importance to human well-being.”
Human health and scientific research
The ocean is thought to be a gold mine of compounds, and its exploration has led to several biomedical breakthroughs.
The first marine-derived drug, Cytarabine, was approved in 1969 for the treatment of leukemia. The medication was isolated from a marine sponge.
Work on bioactive compounds in the venom of cone snails, a type of sea mollusk, led to the development of a potent pain reliever called ziconotide (commercially known as Prialt).
Scientists developed PCR, or polymerase chain reaction, a technique widely used to copy strands of DNA, with the help of an enzyme isolated from a microbe found in marine hydrothermal vents. And a green fluorescent protein observed in jellyfish allows researchers to watch once-invisible processes,including the spread of cancer cells and the development of nerve cells.
These are just a few examples. Researchers say the ocean and the life it contains could provide answers to some of medicine’s biggest challenges, such as antibiotic drug resistance. Studying the sea can also tell us about how life evolved.
“The ocean contains many more of the deep branches of life that have evolved over 4 billion years on Earth and so marine life can tell us a lot about the evolution of both whole organisms and specific biological systems such as developmental genes and immune system,” Rogers said via email.
CNN’s Francesca Street contributed to this story.
There's a reason deep-sea exploration by humans has been so limited: Traveling to the ocean's depths means entering a realm with enormous levels of pressure the farther you descend — a high-risk endeavor. The environment is dark with almost no visibility. The cold temperatures are extreme.Why are the ocean depths so difficult to explore? ›
There's a reason deep-sea exploration by humans has been so limited: Traveling to the ocean's depths means entering a realm with enormous levels of pressure the farther you descend — a high-risk endeavor. The environment is dark with almost no visibility. The cold temperatures are extreme.What are the dangers of ocean exploration? ›
The threat of attack by dangerous marine animals also makes underwater exploration difficult. A host of animals with both defensive and offensive weapons exist in the sea. Some, such as sharks, can easily kill a human. In shark-infested waters, researchers may carry shark repellents.What do we know about deep ocean? ›
Ocean depths greater than 1,000 meters (3,280 feet) are completely devoid of light and photosynthesis does not take place. Sunlight doesn't just provide the energy for photosynthesis: it also heats the water. This means that the deep ocean is also cold – with an average temperature of only 4°C (39°F).Why is ocean exploration worth the risk? ›
Information from ocean exploration can help us understand how we are affecting and being affected by changes in Earth's environment, including changes in weather and climate. Insights from ocean exploration can help us better understand and respond to earthquakes, tsunamis, and other hazards.What 3 factors make it difficult to explore the ocean floor? ›
Answer and Explanation: There are several factors that make the ocean floor difficult to study, such as depth, temperature, pressure and expense.What is the greatest challenge of deep-sea exploration? ›
Deep ocean exploration is a tricky task. Once you go deeper than 200 metres, the ocean gets very dark and very cold. The pressure also greatly increases. All of these factors make it difficult for people to spend time there.What are the five dangers at sea? ›
- Ocean noise. ...
- Ship strikes. ...
- Climate change. ...
- Entanglement in fishing gear. ...
- Plastics and ocean debris.
Overfishing & Destructive Fishing
Overfishing is threatening food security for hundreds of millions of people and destroying ocean ecosystems worldwide. We've already removed at least two-thirds of the large fish in the ocean, and one in three fish populations have collapsed since 1950.
- Ecosystem degradation.
- UN Ocean Conference.
The pressure from the water would push in on the person's body, causing any space that's filled with air to collapse. (The air would be compressed.) So, the lungs would collapse. At the same time, the pressure from the water would push water into the mouth, filling the lungs back up again with water instead of air.What did NASA found in the ocean? ›
To their amazement, the scientists discovered vibrant ecosystems around the vents, teeming with marine organisms, such as translucent snailfish and amphipods, tiny flea-like crustaceans, that had never been seen before.What is below the ocean floor? ›
The ocean floor is called the abyssal plain. Below the ocean floor, there are a few small deeper areas called ocean trenches. Features rising up from the ocean floor include seamounts, volcanic islands and the mid-oceanic ridges and rises.Why should we explore space instead of the ocean? ›
First, exploring space would help us to become a multi-planet species, and hopefully, not so dependent on Earth. Also, there are so many mysteries in space to solve, which would better help us to understand everything from our own rights here on earth, all the way to our entire universe.What is ocean risk? ›
The Ocean, one of the planet's greatest assets, is in crisis. Heating, leading to extreme weather events, sea level rise, and adverse ecosystem changes as well as pollution, overfishing and destructive fishing, rising levels of acidity and biodiversity loss all jeopardise its health.How much of the ocean have we explored? ›
It might be shocking to find out, but only 5% of the ocean has been explored and charted by humans. The rest, especially its depths, are still unknown. In this article, we will learn more about the science of oceanography and the history of ocean exploration throughout the centuries.Why is it sometimes difficult to study the ocean? ›
The ocean is often more difficult to study than the land - a big reason is that it's hard to see what's in there. Humans don't survive well underwater, so we have to come up with all sorts of contraptions to get a peek underneath the surface: SCUBA, submersibles, and ROVs (remotely operated vehicles), for example.What makes it difficult to map the oceans? ›
Mapping the seafloor is very challenging, because we cannot use the same techniques that we would use on land. To map the deep ocean, we use a tool called a multibeam echo-sounder, which is attached to a ship or a submarine vessel.Why is it hard to live in the deep ocean? ›
Organisms living in the deep ocean must be adapted to survive under extreme pressure, limited light, cold temperatures, and other factors. Organisms living in the deep ocean must survive in a physical environment that is radically different from ocean habitats near the sea surface.How deep in ocean can humans go? ›
The maximum depth reached by anyone in a single breath is 702 feet (213.9 metres) and this record was set in 2007 by Herbert Nitsch. He also holds the record for the deepest dive without oxygen – reaching a depth of 831 feet (253.2 metres) but he sustained a brain injury as he was ascending.
Last year an expedition to the Mariana Trench made history by conducting the deepest crewed dive ever completed as it descended 10,927 metres into the Challenger Deep.How deep can we go in the ocean? ›
The deepest part of the ocean is called the Challenger Deep and is located beneath the western Pacific Ocean in the southern end of the Mariana Trench, which runs several hundred kilometers southwest of the U.S. territorial island of Guam. Challenger Deep is approximately 10,935 meters (35,876 feet) deep.What is the biggest threat to humans in the ocean? ›
Global warming is causing sea levels to rise, threatening coastal population centers. Many pesticides and nutrients used in agriculture end up in the coastal waters, resulting in oxygen depletion that kills marine plants and shellfish. Factories and industrial plants discharge sewage and other runoff into the oceans.What causes the most deaths at sea? ›
Sudden Cardiac Arrest can strike anyone at any time, even the fittest and most healthy but the most common cause is a heart attack – a blockage in the arteries which prevents oxygenated blood from reaching the heart.What causes the most harm to the ocean? ›
Most ocean pollution begins on land.
When large tracts of land are plowed, the exposed soil can erode during rainstorms. Much of this runoff flows to the sea, carrying with it agricultural fertilizers and pesticides. Eighty percent of pollution to the marine environment comes from the land.
Weakening economic growth and shifts in international trade will continue in 2023 to impact blue sectors including fisheries, aquaculture and shipping. The rising costs of inputs, fuel and energy have pushed up prices of fisheries and aquaculture products. Shipping faces slowing demand.What are the three major challenges to life in the sea? ›
Toxic spills, oxygen-depleted dead zones, marine debris, increasing ocean temperatures, overfishing, and shoreline development are daily threats to marine life. Part of NOAA's mission is to help protect these organisms and their habitats.What is meant by ghost fishing? ›
Ghost fishing is a term that describes what happens when derelict fishing gear 'continues to fish'. Atlantic croaker trapped within a derelict or "ghost" crab pot pulled from the York River in Virginia.How long can you survive in the deep-sea? ›
A person can survive for around one hour in 5C water, two hours in 10C and six hours in 15C - but if the temperature is in the high 20s then it is possible to survive for around 25 hours, he says.Can humans go to the ocean floor? ›
Thousands have climbed Mount Everest, and a handful of people have walked on the moon. But reaching the lowest part of the ocean? Only three people have ever done that, and one was a U.S. Navy submariner.
The short answer is that there isn't any difference between swimming in deep water and shallow water. Techniques of swimming will work the same way, regardless of the depth below you.Why did NASA stop exploring the moon? ›
The demise was triggered when, in April 1970, an oxygen tank exploded two days after the launch of the Apollo 13 mission, threatening the lives of the astronauts on board. Missions after Apollo 17 were cancelled.What was found in space recently? ›
June 26, 2023 — Scientists detect a new carbon compound in space for the first time. Known as methyl cation (pronounced cat-eye-on) (CH3+), the molecule is important because it aids the formation of more complex carbon-based molecules. Methyl cation was detected in a young star system, with a protoplanetary disk, ...Why did we stop traveling to the moon? ›
Apollo 17 became the last crewed mission to the Moon, for an indefinite amount of time. The main reason for this was money. The cost of getting to the Moon was, ironically, astronomical.Who lives on the ocean floor? ›
Contrary to what one might expect in an ice-covered ocean, the seafloor of the Arctic Ocean is actually teeming with life. These seafloor animals are called “benthos.” The most abundant types of benthos we find are brittle stars, sea cucumbers, sea stars, snails, clams, bristle worms, and, occasionally, crabs.Have humans gone to the bottom of the ocean? ›
This survey confirmed the Challenger Deep as the deepest spot in the world, at more than 36,000 feet below the surface. Only four divers have ever explored the deepest depths of Challenger Deep. In 1960, Jacques Piccard and U.S. Navy Lieutenant Don Walsh explored the Challenger Deep in a submersible called Trieste.Are there bodies of water under the ocean? ›
But did you know that in certain places on the seafloor, like in the Gulf of Mexico, there are even underwater lakes and rivers? How is that possible? Well, these lakes and rivers form when seawater seeps up through thick layers of salt, which are present beneath the seafloor.Why is space infinite? ›
Because space isn't curved they will never meet or drift away from each other. A flat universe could be infinite: imagine a 2D piece of paper that stretches out forever. But it could also be finite: imagine taking a piece of paper, making a cylinder and joining the ends to make a torus (doughnut) shape.What is the deepest part of the ocean? › What is needed to explore the ocean? ›
Technologies include platforms such as vessels and submersibles, observing systems and sensors, communication technologies, and diving technologies that transport us across ocean waters and into the depths and allow us to scientifically examine, record, and analyze the mysteries of the ocean.
More than 80 percent of the ocean has never been mapped, explored, or even seen by humans. A far greater percentage of the surfaces of the moon and the planet Mars has been mapped and studied than of our own ocean floor. Although there is much more to learn, oceanographers have already made some amazing discoveries.Is 80% of the ocean not explored? ›
More than eighty percent of our ocean is unmapped, unobserved, and unexplored. Much remains to be learned from exploring the mysteries of the deep.How much of the Earth is still unexplored? ›
Just 5% of Earth's landscape is untouched.Why has it been so difficult to map the ocean floor? ›
The reason, Feldman noted, largely comes down to cost. Boats equipped with sonar technology can rack up exorbitant expenses. Fuel alone can total up to $40,000 per day, Feldman said. There is, however, currently an effort underway to create a definitive map of the ocean floor, called Seabed 2030.Why is it difficult to map the ocean floor? ›
Mapping the seafloor is very challenging, because we cannot use the same techniques that we would use on land. To map the deep ocean, we use a tool called a multibeam echo-sounder, which is attached to a ship or a submarine vessel.Why is the ocean so hard to map? ›
The ocean is big, deep and impermeable to the laser altimeter that made mapping our less watery neighbor planets possible. To complete a map of Earth's ocean floor, you've got to take to the high seas by boat.Why can't humans swim to the bottom of the ocean? ›
The water is heavier than air, and therefore puts more pressure on us and objects in the sea. The deeper you go into the ocean, the more water there is above you, so there is more pressure. Our human bodies - specifically our lungs - are only designed to manage one atmosphere's worth of pressure (like we do on land).Is there a crack in the ocean floor? ›
The crack is called a rift and the constant filling of the widening crack is called seafloor spreading. Nearly all of the areas of Planet Earth under the oceans have been formed in this way.What happens when you go to deep in the ocean? ›
The deeper you go under the sea, the greater the pressure of the water pushing down on you. For every 33 feet (10.06 meters) you go down, the pressure increases by one atmosphere . Many animals that live in the sea have no trouble at all with high pressure.Has anyone reached the ocean floor? ›
But reaching the lowest part of the ocean? Only three people have ever done that, and one was a U.S. Navy submariner. In the Pacific Ocean, somewhere between Guam and the Philippines, lies the Marianas Trench, also known as the Mariana Trench.
The main reason for our lack of direct observations of our ocean floor is technological. The surface of the Earth, the Moon and/or Mars are directly illuminated by light and radio waves.How much of the ocean is unexplored? ›
Our oceans cover more than 70% of the Earth's surface, but over 80% of them remain unexplored. In fact, it is often claimed that we know more about the surface of Mars and the Moon than about the ocean floor on our own planet.How were they able to map the ocean floor? ›
Multibeam sonar signals are sent out from the ship. With about 1500 sonar soundings sent out per second, multibeam “paints” the seafloor in a fanlike pattern. This creates a detailed “sound map” that shows ocean depth, bottom type, and topographic features.Why is it so hard to live in the deep ocean? ›
Organisms living in the deep ocean must be adapted to survive under extreme pressure, limited light, cold temperatures, and other factors. Organisms living in the deep ocean must survive in a physical environment that is radically different from ocean habitats near the sea surface.Why is the ocean so rough? ›
Waves are most commonly caused by wind. Wind-driven waves, or surface waves, are created by the friction between wind and surface water. As wind blows across the surface of the ocean or a lake, the continual disturbance creates a wave crest.How deep can a human go underwater without dying? ›
While the recommended maximum depth for conventional scuba diving is 130 feet, technical divers may work in the range of 170 feet to 350 feet, sometimes even deeper.Can the ocean pressure crush you? ›
Too much pressure would collapse those spaces, crushing us. Animals adapted to deep-ocean life don't have air pockets in their bodies. Some marine animals travel between deep ocean and the surface.