Isn’t that like living in a house you’ve only been to two rooms of ten? The rest will be a mystery — behind locked doors and secrets you’ve never laid eyes on. That, right there, is how human beings interact with the oceans of the Earth. We have mapped every corner of Mars, sent probes beyond our solar system and photographed galaxies light-years away. And yet it all unfolds right here on our little blue dot: More than 80 percent of the ocean is unmapped, unobserved and unexplored.
This is more than just a fun fact to share at parties. The undiscovered ocean has answers to some of humanity’s most pressing questions: Where did life originate? What drugs could cure our ailments? How could we better estimate natural disasters? What resources lie beneath the waves? The ocean occupies 71 percent of Earth’s surface, it holds 97% of our planet’s water, and it has produced at least 50% of the oxygen in our atmosphere. Nevertheless: What we do know about the surface of the moon dwarfs what we know about our own ocean floor.
This article delves deeply into the reality of what we know and don’t know about our oceans, why that is and what the latest scientific findings mean for our future.
Why Most of the Ocean Is Mysterious
The simple answer? The ocean is marvelously hard to get to know. But let’s consider just why this huge portion of our world is still an enigma.
Extreme Pressure That Crushes Everything
The further you go down, the more water pressure mounts. The pressure at the average ocean depth, some 12,100 feet, is over 5,600 pounds per square inch. It is as if a giant elephant were standing on the face of your thumb. At its lowest point — the Challenger Deep of the Mariana Trench — the pressure is greater than 16,000 pounds per square inch. Regular submarines can’t handle this. Building a container that can withstand these crushing forces costs millions of dollars and calls for cutting-edge technology.
Complete Darkness Below the Surface
Sunlight can penetrate only 660 feet below the ocean surface. Below that? Total darkness. That means everything has to be lighted artificially, which demands a tremendous amount of power. Sensors and detectors fail in those conditions. Many deep-sea species have evolved to be entirely lightless, and that has made them all the stranger — and more difficult to study.
Freezing Cold Temperatures
The deep ocean waters, for example, are just a bit above freezing—usually between 32°F and 37°F. This frigid chill can impact equipment, drain batteries more quickly and generally make missions much harder to accomplish. The application of harsh substances is a need due to equipment failure in such tough conditions.
Vast Size and Remote Locations
The ocean covers roughly 139 million square miles. To give some sense of scale: To map the entire ocean floor with sonar from a ship would take one vessel about 200 years of nonstop work. The most attractive, unexplored sections are usually in the middle of nowhere – far away from any coast and an expensive expedition.
Limited Technology Until Recently
For most of human history, we didn’t have the technology to venture into deep waters. The original diving bells could descend only a few hundred feet. Submarines had not been invented in the 20th century. Microscopic unmanned vehicles such as remotely operated vehicles (ROVs) and autonomous underwater vehicles (AUVs) are a relatively new creation. Satellite technology that can map ocean floors through water is newer still.
High Costs of Deep-Sea Missions
A single deep-sea expedition can cost hundreds of thousands or even millions of dollars. Research vessels, special equipment, trained crews and the long duration of missions all cost money. Space exploration generally gets more funding, because it can capture the public imagination. The deep ocean, sitting much closer to home, feels somehow less interesting to many people — yet it shouldn’t.
What We Know So Far
While most of the ocean is uncharted, what we do know is simply mind-boggling. That strikes at the heart of what we understand about life, Earth’s history and the planet’s future.
Strange Creatures That Defy Logic
The deep sea contains some of the oddest life on this planet. The anglerfish dangles a lit lure to lay claim of prey in the pitch black. Giant squids can be up to 43 feet long. Blobfish look like melted faces. Barreleye fish have heads as clear as glass so you can see their brains. These are not creatures of science fiction — they’re real animals that have evolved to survive the most extreme conditions we only now begin to understand.
Hydrothermal Vents and New Life Forms
In 1977, scientists found hydrothermal vents — fissures in the ocean floor from which superheated water, some of it up to 750 degrees Fahrenheit, spews into the water around it along with minerals. Entire ecosystems thrive without sunshine around these vents. Chemosynthesis provides energy in place of photosynthesis, where organisms derive energy from chemicals in the hot water. This finding expanded our realm of understanding about where life can live — on both this and other planets.
Underwater Mountains and Massive Canyons
The ocean floor isn’t flat. It harbors a sprawling mountain range larger than any found on land. It extends to about 10,000 miles long. In the Mariana Trench, the water plunges to almost 36,000 feet—farther down than Mount Everest is high. We’ve discovered underwater volcanoes, large plains and intricately layered geological formations that tell the tale of our planet’s past.
Shipwrecks and Lost Cities
The bottom of the ocean is a museum of human history. We’ve found ancient shipwrecks laden with valuable cargo, missing World War II-era submarines and even remains of long-lost civilizations devoured by rising seas. Every find offers hints about how humans lived, traveled and traded in the distant past.
Plastic and Pollution Everywhere
Regrettably, exploration has uncovered a crude reality: Human pollution has muddied even the deepest-lying parts of the ocean. Plastic bags have been discovered at the bottom of the Mariana Trench. Microplastics are found in nearly all water samples taken. Enormous swathes of the area are polluted with chemical pollutants, heavy metals and other human waste. The ocean is not the pristine wilderness that so many of us imagined.
The Ocean Floor Map: Is This the Best We’ve Got?
| Ocean Region | Percentage Mapped | Mapping Method | When Completed/Updated |
|---|---|---|---|
| Shallow Coastal Waters | 90 to 95% | Sonar, Satellite | Continually Updatable |
| Continental Shelf | 70 to 80% | Ship-based Sonar | Continuing |
| Deep Ocean Floor | 20 to 25% | Satellite Altimetry, Sonar | New Data (update) 2023 |
| Mariana Trench | <5% | Specialized Detailed ROVs | Several Missions Hosted |
| Mid-Ocean Ridges | 30 to 40% | AUVs and Ship Surveys | Ongoing |
| Polar Ocean Regions | ~40–50% | Icebreakers & Satellites | Expanding |
This table demonstrates that we’ve done some work on it, but most of the world’s detailed mapping is still incomplete. Satellite technology can draw rough maps of the ocean floor by taking measurements of minuscule changes in sea level — but these merely show low-resolution images. For more detailed maps that include individual features, we rely on ships equipped with sonar — which is much slower and costlier.
Modern Technology Changing Ocean Exploration
The past two decades have seen revolutionary developments in the way we study the ocean. We are finally getting the technologies to unlock some of the ocean’s secrets.
Autonomous Underwater Vehicles (AUVs)
One can dive deep, and both are unmanned. They are programmed to follow predetermined paths, collect data, snap pictures and obtain samples. Some can remain submerged for months, and travel great distances. They are cheaper than crewed missions and can assume risks that would threaten human life.
Remotely Operated Vehicles (ROVs)
ROVs are held on the surface by a cable, so must be controlled in real-time. They are capable of reaching great depths, and can send samples to the surface as well as live video images. ROV Deep Discoverer has discovered countless new species and geological features.
Advanced Sonar Systems
State-of-the-art multibeam sonar can map the seafloor in breathtaking detail. They project sound waves that reflect off the seafloor, forming 3D images of underwater terrain. Ship-based systems are getting more powerful and efficient, meaning faster mapping of larger areas.
Satellite Technology
Satellites record the height of the ocean surface with exquisite accuracy. As water accumulates a bit above underwater mountains and slides down into trenches (courtesy of gravity), satellites can detect these slight changes and construct maps of the seafloor. Not as granular as sonar, but it allows us to map great areas in short order.
Deep-Sea Submersibles for Humans
New submersibles can carry humans to the deepest parts of the ocean. The Limiting Factor submarine, operated by Victor Vescovo, has made several dives into the depths of the Mariana Trench. Because these crewed missions offer a human point of view that robots cannot match, they generate public interest in exploring the oceans.
Artificial Intelligence and Machine Learning
AI aids scientists in analyzing the huge amount of data gathered on ocean field missions. Machine learning algorithms can find new species in photographs, map currents, predict the behavior of animals and discover patterns that humans may never see: technology to analyze ocean data at a rate unprecedented in human history.
Why the Ocean Needs Our Attention Now
So why should we spend money exploring the ocean, some ask, when we have so many other problems? The reality is, ocean research addresses many of the challenges confronting humanity.
Climate Change Answers
The sea absorbs roughly 30 percent of the carbon dioxide we emit and more than 90 percent of the excess heat from global warming. How much more can it handle? And what if it reaches its limit? Where do these currents take that heat, and how do they help manage the planet’s climate? To accurately predict climate change and plan our response, we need detailed ocean data.
New Medicines and Treatments
The deep sea is home to special chemical compounds that have evolved in organisms living at extreme conditions. Researchers have already turned marine organisms into cancer drugs, painkillers and antibiotics. The ocean’s unexplored expanses would probably hold thousands more species with medical potential. We could be swimming by cures for the diseases that afflict us.
Feeding a Growing World Population
The ocean provides the primary source of protein for more than three billion people. As the world population nears eight billion, we have to learn more about ocean ecosystems to harvest fisheries sustainably. Many fish populations have been overfished; we need better data to keep food sources from collapsing.
Natural Disaster Prediction
Underwater earthquakes cause tsunamis. Global temperature patterns affect hurricanes and typhoons. Geological and current processes in the ocean also help us to predict and prepare for natural disasters. Better ocean data equals better warning systems, and fewer people killed.
Resources and Energy
The seabed hosts abundant rare minerals, metals, and energy resources. It could offer materials required for electronics, batteries and renewable energy technology through underwater mining. But we need to know about ocean ecosystems before extracting these resources, or we could end up wrecking environments that people have never set eyes on.
National Security and Sovereignty
Many countries lay claim to sections of the ocean floor for economic reasons. Precise maps establish who dominates which turf. Submarine activity, underwater cables pulsing with internet traffic and covert military installations make the collection of ocean knowledge a matter of national security.
The Deepest Dive: What We Found in the Mariana Trench
| Dive Record | Depth Reached | Year | Explorer/Vehicle | Notable Discoveries |
|---|---|---|---|---|
| Trieste | 35,797 feet | 1960 | Jacques Piccard, Don Walsh | First humans to reach bottom, observed flatfish and shrimp |
| Kaiko ROV | 35,798 feet | 1995 | Japanese Unmanned | Collected samples, uncovered evidence of bacteria |
| Deepsea Challenger | 35,756 feet | 2012 | James Cameron | Filmed documentary footage |
| Limiting Factor (First) | 35,843 feet | 2019 | Victor Vescovo | New depth record set, found a plastic bag |
| Limiting Factor (Multiple) | Reached on five dives | 2019 | Various scientists | Multiple species discovered; pollution and geological sample collection |
These trips to the bottom of the Earth have shown us life lurks even at the most unimaginably harsh settings. And they have demonstrated that human pollution has penetrated even these remote depths, a bracing reminder of our impact on the planet.
Greatest Myths of the Uncharted Ocean
Myth 1: There’s Nothing in the Sea but Water
The vast seabed is a forbidding place, and many people think the deep ocean is mostly empty of life: no food, no company in the form of other creatures. Reality? The sea is full of life from top to bottom. Life also forms complex ecosystems in zones that are dark, cold and under tremendous pressure. The diversity of life in the ocean may surpass that on land.
Myth 2: We’ve Seen It All, or at Least Most of It
People seem to think that we’ve already discovered anything significant there is in the ocean. This couldn’t be more wrong. New species are discovered regularly. New major geological features are still being discovered. Every expedition reveals surprises.
Myth 3: Satellites Have Mapped All There Is to Map
Satellites map the ocean floor in a crude way, but in their maps much of it remains uncharted. They are able to display large-scale features, but can lose anything smaller than about three miles across. To really explore, we need ships and submarines, which have touched only a tiny portion of the ocean.
Myth 4: There’s Not Much of Interest (Geologically Speaking) on the Ocean Floor
In fact, the floor of the ocean has more dramatic features than earth’s surface. The most massive mountains, deepest canyon, most active volcanoes and dynamic geological features exist beneath the sea. The seafloor, after all, is always transforming — new terrain is born.
Myth 5: The Costs of Exploring the Deep Ocean Are Just Too High
Exploring the ocean is expensive, but the cost-benefits are staggering. This includes medical advances, climate data, food security and the responsible use of resources among others. The return on investment is huge — we just need patience to see the payoff.
What Lurks in the Unexplored Depths of the Ocean?
There are plenty of theories among explorers and scientists about what still waits to be discovered. A few are grounded in evidence, some more speculative.
Millions of Unknown Species
The latest estimates have it that we’ve found less than 10 percent of ocean species. Millions of species, from tiny bacteria to lanky fish and towering marine mammals, remain unidentified. Every new expedition uncovers dozens, or sometimes hundreds of new species.
Ancient Geological Formations
The youngest rocks ever to have been found on the planet are those on the sea floor. Studying these areas might offer clues about how our planet formed and the early history of Earth. Find out evidence for ancient meteor impacts, volcanic events or long-term changes in the crust of Earth that altered the course of planetary evolution.
Underwater Archaeological Treasures
Thousands more ships still lie unlocated, with plenty likely holding valuable treasure or other historical artifacts. And somewhere below the waves are once-great cities drowned by rising seas. These are the kinds of sites that could redefine what we know about ancient civilizations.
New Energy Sources
Scientists are looking at potential cooperation between bacteria that live near hydrothermal vents and make both methane and other compounds. They could even provide models for new renewable energy technologies. Huge amounts of methane hydrates — frozen methane trapped in ice — can also be found across the ocean, potentially as an energy source or a climate threat.
Traces of Life on Other Planets
If life can live in the extreme environments of the deep oceans, they might exist in Jupiter’s moon Europa or Saturn’s moon Enceladus, which has underwater oceans. Studying the ocean on Earth helps us learn where and how to look for life elsewhere. Learn more about ocean exploration from NOAA.
Obstacles to Ocean Science
Besides the most obvious challenges of navigating an abyss, there are many practical obstacles slowing research.
Underfunding Compared to Space
NASA’s budget is millions of times greater than the funding available to study the oceans. NOAA gets a pittance of funding compared with NASA—while in reality, the ocean is far more critical to human existence. Space exploration is associated with more public excitement and therefore it’s easier to find funding — oceanic research, not so much.
International Cooperation Difficulties
The ocean knows no border. Large-scale exploration needs international collaboration, open data sharing and concerted actions. This cooperation is complex and fraught with political tensions, conflicting interests, and territorial demands.
Data Storage and Processing
A single expedition produces terabytes of data — sonar readings, video, sensor measurements, samples and more. It would be computationally expensive and time-consuming to process, store and analyze this information. Databases are full of discoveries for which someone has yet to analyze their contents.
Training Specialized Personnel
The operation of deep-sea vehicles, the analysis of ocean data and marine research all demand specialized expertise. Training programs are few, and we don’t even have enough qualified people to man all the research missions we’d like to undertake.
Equipment Maintenance and Development
Saltwater corrodes equipment aggressively. The harsh environment is brutal on even the most durable substances. It takes years of work and costs millions to develop new technology that can endure ocean conditions. Existing hardware needs a lot of maintenance.
What’s Next: The Future of Ocean Exploration
We are entering the most exciting period of ocean exploration in the next few decades. There are some big projects going in that will revolutionize our understanding.
Seabed 2030 Project
This worldwide effort has a goal to map the entire ocean floor by 2030. With upgraded technology, crowdsourced data and international collaboration, the team has already doubled the patch of ocean floor it was initially able to map. Hitting the 2030 target is an ambitious goal, but this project is actually making concrete progress.
Ocean Census
This ten-year initiative began in 2023 and will seek to find 100,000 new species from the sea. Through rapid DNA sequencing, AI-driven image recognition and collaborative research efforts — a kind of collective intelligence for the sea-world — scientists are hoping to greatly expand our inventory of oceanic life.
Improved Submarine Technology
Submarines of the future will go deeper, endure longer and operate more autonomously. Some designs feature piloting by AI that can make decisions without human guidance. Others have modular designs that enable them to be customized for various missions.
Ocean Internet of Things
Thousands of sensors will be spaced out over the ocean, part of researchers’ plan to establish a monitoring network in real time. These sensors measure temperature, salinity, currents, chemistry and wildlife activity. The data are fed into models that allow us to be better ocean forecasters.
Commercial Ocean Exploration
Private firms are showing a growing interest in ocean exploration. Some are centered on mining potential, some on tourism, and some around pure research. This business interest attracts extra funding and ideas to the sector.
Frequently Asked Questions
How much of the seas have been discovered?
The ocean floor, which comprises 70 percent of the Earth’s surface, is only mapped in detail in about 20-25 percent of it and directly explored by humans or robots in less than 5 percent. Most of what we know about the oceans comes from sonar mapping and satellite data, which yield general information but lack details.
Why is the ocean so much more difficult to explore than space?
The pressure of the oceans, the darkness and corrosion combine for challenges that space exploration doesn’t have. The pressure in water grows rapidly along the depth axis, so deep-diving vehicles must be very strong. Darkness requires constant artificial lighting. Saltwater corrodes equipment. It is infinitely more difficult to communicate underwater than in space, because radio waves do not travel through water easily.
Do we actually have unknown animals in the deep ocean?
Absolutely. On most deep sea expeditions, scientists turn up dozens of new species. Estimates are that 91 percent of ocean species have yet to be discovered. These could be anywhere from an organism invisible to the naked eye to a creature the size of a room that we’ve never glimpsed before.
Is it possible a megalodon still swims the depths of the uncharted ocean?
Almost certainly not. While huge swaths of the ocean have not been explored, megalodons were giant sharks that would require huge amounts of food to survive. We would see signs of one feeding — missing whale populations, bite marks on big fish and others. The food chain likely could not have supported such gargantuan predators in sufficient numbers for a breeding population.
What is the most shocking discovery ever found in the ocean?
The discovery of hydrothermal vents and their lifeforms is often considered by many scientists to be the most surprising. Until 1977, it was a universal article of faith that life needed sunlight. Discovering complex ecosystems that thrive in complete darkness, by virtue of chemical energy instead of solar energy, revolutionized biology and revolutionized our understanding of where life could be.
Is the bottom of the ocean really deeper than mountains are high?
Yes. The Challenger Deep in the Mariana Trench is about 36,000 feet (or nearly seven miles) beneath the sea surface. Mount Everest has a peak that’s approximately 29,000 feet above sea level. Even if you dropped Mount Everest into the Challenger Deep, the top of that mountain would still be more than a mile under water.
How long is it to discover all the ocean?
And using current technology and funding, the detailed exploration and mapping of all parts of the ocean floor would require centuries to fully complete. The Seabed 2030 project, for example, seeks to draw up basic maps of the entire ocean floor by 2030, but detailed surveys in each area would take much longer and far more resources.
What can people do to help the exploration of the ocean?
Support these organizations that fund ocean research, decrease your own plastic use, make sustainable seafood choices and spread the word about issues impacting the ocean. Public interest funds these expeditions, and so knowledge-sharing about ocean exploration is beneficial. Some projects also enable citizen scientists to help classify ocean photos or analyze data at home.
And Finally: What the Mysterious Ocean Means to You
The ocean impacts you where you live, in ways that you may not feel or even immediately see. The seafood you consume is harvested from waters we scarcely know. The weather systems that shape your home originate in ocean currents we are still charting. Organisms we haven’t even found yet might represent the drugs that cure your diseases within your lifetime.
Each time we go deeper into the ocean, novel specimens upend all that we thought we knew about Earth and life. We find new species that would never work according to our old theories. We run into geological features that rewrite planetary history. We discover signs of human interference in what we believed to be impossible-to-reach places.
The ocean is the source of most of our oxygen, and it absorbs a quarter of carbon dioxide emissions. It helps regulate our atmosphere, feeds billions of people and contains answers to questions we’re just now starting to ask. It’s not simply to satisfy curiosity — although that would in itself be a good thing. This is about knowing the planet we live on and guaranteeing a future that will be livable for generations to come.
The reality about the unknown 80 percent of our oceans is straightforward: we inhabit a planet of which we know next to nothing. We looked up to the stars rather than down at the wilderness below. That’s finally changing. In a new era of ocean exploration, with new technology and renewed concern — and pressing questions about climate change and preserving the planet — ocean exploration is being reimagined.
What we discover over the coming decades will probably be surprising, challenge what we think we know, and shift our understanding of life on Earth and our place in the universe. For millions of years, the oceans’ secrets have waited. Now, finally, we’re building the tools and resolve to see what’s revealed.
The next big age of exploration is not in the stars but in the deep blue sea that covers most of our own planet. And what we find there could ultimately save us all.
