The ocean covers over 70% of the planet, yet it largely remains a mystery to us. There is a common belief that we have explored less than 5% of the global ocean. This idea that 95% of the ocean is undiscovered is widely quoted, but where does this number come from and is it accurate? In this article, we’ll break down the facts and statistics to determine how much of the ocean truly remains unexplored.
Defining “Undiscovered Ocean”
To start, we need to define what constitutes “undiscovered ocean.” The ocean is vast, so discoveries can range from mapping the seafloor to sampling water chemistry to identifying new species. For our purposes, let’s focus the definition on seafloor mapping – determining the depth, shape, and features of the ocean bottom using sonar or other technologies. This provides insights into seabed terrain, plate tectonics, and environments where marine life may exist.
Seafloor mapping provides a concrete way to quantify ocean exploration. We can compare the total seabed area to the area that has been mapped at reasonable resolution. This gives an estimate of how much of the physical ocean floor terrain remains undiscovered, even if we don’t know exactly what lives there yet.
History of Ocean Exploration
Humans have been exploring the oceans for thousands of years, but detailed seabed mapping only became possible in the 20th century. Early ocean surveys used weighted lines or poles to measure depths, providing sparse coverage along limited routes. However, the development of sonar during World War II allowed much more comprehensive mapping.
Ship-mounted sonar systems enabled the first global surveys of ocean basins in the 1950s and 1960s. Since then, technologies have improved dramatically. Satellites can now derive seabed depth from subtle variations in sea surface height. Autonomous underwater vehicles (AUVs) can map large swaths of seafloor at high resolution. Despite this progress, mapping the entire ocean floor in detail remains a vast undertaking.
How Much of the Seafloor Has Been Mapped?
Currently, we have high-resolution bathymetric data for about 20% of the global ocean floor, predominantly in areas of commercial interest and around coastlines. The remaining 80% has coarser resolution or remains completely unmapped. The map below gives a visual representation of mapped vs unmapped areas.
This 20% figure is only for high-resolution seafloor mapping data accurate to 100 meters or finer detail. If we include coarser global surveys, estimates for mapped ocean floor range from 40-50% complete. Either way, the majority of the seabed remains unmapped at high resolution.
Challenges in Ocean Exploration
Why do such large gaps remain in seafloor mapping? The ocean presents unique challenges:
– Vast areas: The seafloor has a surface area of over 360 million square kilometers, nearly 90 times larger than land. Surveying at high resolution requires systematic mapping lane by lane.
– Remote locations: Much of the ocean, especially the southern hemisphere, is distant from land bases. This complicates logistics and transit for survey ships.
– Harsh conditions: Storms, waves, and deep water make seafloor mapping difficult. Most of the ocean is over 2 km deep, beyond where sunlight reaches.
– Resource limitations: Ship time and sonar equipment for mapping are expensive. Most ocean research has focused on biology rather than seabed geology.
– Low priority: Beyond navigational safety, there are few economic motivations for countries to map remote abyssal plains that lack resources.
– Classified data: Some ocean data was kept classified for military purposes during the Cold War era, limiting information sharing.
Together these challenges help explain why seafloor mapping has progressed relatively slowly. But new technologies and motivations are expanding ocean data collection today.
Expanding Ocean Mapping and Exploration
Despite the difficulties, ocean mapping initiatives have set ambitious goals for filling in seabed data worldwide. Here are some key efforts and innovations:
– The Nippon Foundation-GEBCO Seabed 2030 Project aims to bring together all available bathymetric data to produce a complete high resolution map of the ocean floor by 2030.
– AUVs and autonomous surface vehicles can efficiently survey large areas without a human crew onboard. Machine learning improves navigation and sensor data analysis.
– Crowdsourcing engages citizen scientists in analyzing images and data to accelerate mapping.
– Satellite-derived gravity maps provide moderate resolution coverage of unsurveyed areas in the deep ocean.
– Participation by industry and philanthropic organizations leverages new resources for open ocean research.
– Artificial intelligence and cloud computing enable compiling regional surveys into a global database more rapidly.
How Much is Truly Undiscovered?
Given these mapping initiatives, what portion of the deep seafloor is realistically undiscovered today?
While 20% has high resolution bathymetric mapping, an additional 30% of the ocean floor has been covered by sparse ship depth soundings or satellite altimetry. These provide coarse resolution of major seafloor features. Approximately 50% now has some form of bathymetric control.
The remaining 50% has never been directly measured for depth or sampled. This includes remote portions of the Atlantic, Indian, and Pacific oceans. These abyssal plain areas are undoubtedly vast frontiers for future discovery even at low resolutions.
With continued international efforts, experts estimate complete high resolution mapping of the global ocean floor could be achievable by 2040.
More Than Just Mapping
Keep in mind that bathymetric mapping is only one aspect of ocean exploration. The chemistry, biology, and geology of the underwater world remain vastly under-sampled almost everywhere. We have better maps of Mars and the Moon than of Earth’s seafloor.
Less than 0.05% of the ocean has been directly sampled with sediment cores, dredges, or submersibles. Over 80% of the ocean lacks even a single biological sample. New species are routinely discovered on every deep-sea science expedition.
Our knowledge remains extremely limited about deep sea ecosystems and the diversity of life across ocean basins and trenches. There are likely millions of undiscovered species in the deep sea and seafloor sediment alone.
So while half of the ocean floor terrain has been loosely mapped, over 95% remains completely unexplored and unsampled for what actually lives there. The discovery potential is immense.
Conclusion
The idea that 95% of the ocean is undiscovered is not quite accurate based on seafloor mapping progress. A better estimate is that roughly 50% of the seabed remains unmapped at high resolution, with this area concentrated in the southern hemisphere and remote oligotrophic gyres.
However, over 95% of the ocean remains unexplored and unsampled for biodiversity, species, and ecosystems. Our knowledge of ocean chemistry, biology, and deep sea geology is still remarkably sparse in most regions.
Tremendous potential clearly exists for discovery through expanded systematic exploration. New technologies are allowing us to finally map, sample, and study the vast depths of this last frontier on Earth. Dedicated international efforts aim to continually expand our knowledge of the global ocean this century.