It may come as a surprise to many that the unexplored depths of Earth’s oceans are far more enigmatic to scientists than the surface of the moon, which is located approximately 240,000 miles away in space. This stark contrast highlights the challenges faced in ocean exploration compared to lunar studies. Over the years, spacecraft have successfully mapped the lunar landscape, revealing intricate features and geological formations. In contrast, the mapping of the ocean floor presents unique obstacles. The immense water pressure found in these deep-sea environments can easily crush most equipment. Additionally, the ocean’s vast expanse obscures the seafloor beneath miles of water, which absorbs light, rendering direct observation particularly challenging.

A groundbreaking initiative utilizing data from a NASA-led satellite is revolutionizing our understanding of the ocean floor, providing one of the most comprehensive maps ever created of the world’s underwater terrain. The SWOT satellite, which stands for Surface Water and Ocean Topography, represents a collaborative effort between NASA and the French space agency, the Centre National d’Études Spatiales. This innovative satellite is not only enhancing our knowledge of hydrological features but also offering unprecedented insights into the underwater landscape.

“This satellite represents a significant advancement in our ability to accurately map the seafloor,” stated David Sandwell, a geophysicist at the Scripps Institution of Oceanography, in a recent statement. The capabilities of the SWOT satellite are truly transformative, as they allow scientists to gather data that was previously out of reach, opening new avenues for research in marine science and geology.

Launched in December 2022, the satellite was originally designed to measure water height across the planet’s oceans, lakes, and rivers. Although its primary function was not seafloor mapping, scientists have discovered that its advanced technology allows for more accurate estimations of the size and shape of underwater structures. This unexpected application of the satellite’s capabilities has opened exciting new pathways for oceanographic research, enhancing our understanding of marine environments.

Experts from various scientific disciplines stress the importance of understanding the ocean floor. Detailed maps are essential for safe navigation of ships, helping to avoid potential hazards, and guiding engineers in the installation of underwater communication cables. Moreover, these maps are crucial for studying deep-sea currents, tidal movements, and the dynamics of Earth’s tectonic plates—the massive segments of the planet’s crust that shift and change over extensive periods. Such knowledge is invaluable for both ecological and geological research, enabling better predictions about natural phenomena.

For years, researchers have employed traditional methods to map the ocean floor, utilizing ships and sonar technology—which sends sound waves that bounce off the seabed to measure depth. However, this slow process has limited coverage, as ships can only survey small sections at a time, leaving vast areas of the ocean unexplored and uncharted. This inefficiency in mapping has hindered our comprehensive understanding of marine landscapes and their complexities.

The slow progress in ocean mapping raises concerns that scientists may not achieve their goal of producing a complete seabed map by 2030. Despite the increasing number of satellites in low-Earth orbit, most of them lack the necessary resolution to rival that of sonar. However, the data obtained from SWOT is approximately twice as detailed as previous satellite maps, making it significantly easier to identify previously unknown underwater features. A new SWOT-based seafloor map was published in the journal Science in December, showcasing these advancements.

NASA has created an animation, displayed above, that illustrates some of the new insights gained from the SWOT data, including details from regions off the coasts of Mexico, South America, and the Antarctic Peninsula. In this representation, purple areas indicate lower regions adjacent to higher underwater elevations, which are depicted in green. This visualization helps to convey the complex topography of the ocean floor and the newly discovered features that are vital for marine research.

SWOT’s innovative radar technology has enabled it to identify seamounts that are less than half the size of those previously documented, potentially increasing the known number of seamounts from around 44,000 to a staggering 100,000. These underwater mountains play a critical role in influencing ocean currents and can create nutrient-rich environments that attract diverse marine life. Understanding these features is essential for ecosystem management and conservation efforts.

“We won’t complete ship-based mapping by 2030,” Sandwell stated. “However, SWOT will significantly aid us in filling in the gaps.” This acknowledgement emphasizes the importance of integrating various mapping technologies to enhance our understanding of the ocean floor and its complexities.

Here’s how the technology functions: The satellite detects minute changes in the height of the ocean surface. Rather than observing the sea as a perfectly flat expanse, it is actually uneven. Submerged mountains and various geological formations exert stronger gravitational forces than their surroundings, leading to slight elevations in water height. These subtle variations can be accurately measured by SWOT’s sophisticated instruments, allowing for a deeper understanding of the marine landscape. The satellite effectively scans 90 percent of the planet as it completes its orbit every 21 days.

The SWOT satellite sweeps over 90 percent of the planet as it orbits every 21 days.
Credit: NASA / JPL-Caltech / CNES / Thales Alenia Space illustration

According to the findings published in Science, SWOT has gathered more detailed data in just one year than what was collected over the past 30 years by older satellite missions. The new map boasts a resolution of approximately 5 miles, allowing scientists to detect features that previously escaped their notice.

This enhanced clarity has enabled researchers to identify underwater ridges known as “abyssal hills,” which have been shaped over time by gradual tectonic shifts. These hills are the most prevalent topographical feature on Earth, covering about 70 percent of the ocean floor, which itself encompasses roughly 70 percent of the planet’s surface. Because they are smaller than seamounts, existing satellites have struggled to detect these features, highlighting the necessity for advanced mapping technologies.

The improved maps generated by SWOT could pave the way for new geological discoveries, such as identifying active underwater volcanoes and previously uncharted fault lines. There is also the potential to rediscover ancient landforms that have remained submerged beneath the waves. Each of these revelations holds significant implications for our understanding of Earth’s geological history and the processes that shape our planet.

Moreover, astrobiologists stand to benefit from these discoveries. Many scientists have theorized that the essential chemistry for the emergence of life on Earth originated at mid-ocean ridges, where tectonic plates diverge. This geological activity can give rise to hydrothermal vents, environments characterized by superheated water rich in minerals. The data gathered from SWOT may assist researchers in locating new underwater hot springs for further investigation, potentially enhancing our understanding of the conditions that foster life, both on Earth and in extraterrestrial environments.