When people think of the highest form of exploration, they often picture astronauts floating through space or rovers driving across Mars. Yet one of the greatest mysteries isn’t millions of light-years away; it is right here on Earth.
A popular fact you often hear is that “we’ve explored more of space than our own oceans.” While this isn’t entirely factual, there is truth behind the statement. Scientists have mapped the Moon and Mars in extraordinary detail, but much of the ocean remains largely unexplored, despite it covering more than 70% of the Earth’s surface.
So why is it so difficult to explore somewhere that’s literally on our own planet?
The biggest challenge faced is pressure. At sea level, we live at 1 atm (atmosphere) of pressure. In the vacuum of space, there are essentially 0 atm. The difference in pressure between standing on Earth’s surface and floating in space is only about 1 atm. The ocean is a completely different story. For every 10 meters you descend underwater, the pressure increases by another 1 atm. At the deepest known point on Earth, the Mariana Trench, the pressure reaches more than 1100 atm.
Astrophysicist Neil deGrasse Tyson elaborates that surviving extreme pressure is often a greater engineering challenge than surviving the vacuum of space. In space, the pressure needs to be kept inside the spacecraft. Deep underwater, the vessel must constantly prevent immense pressure outside from crushing everything inside. To imagine how extreme that pressure is, picture the weight of thousands of elephants pressing on your shoulders.
Deepsea Challenger (Image credit: National Geographic)
Pressure isn’t the only obstacle. Sunlight can only penetrate about 200 meters into the ocean. Below this lies the “midnight zone” where complete and total darkness has existed for millions of years.
The oceans’ sheer size also makes exploration incredibly time-consuming; covering approximately 361 million square kilometres, it is the Earth’s largest habitat. Even with modern technology, mapping the seabed in high resolution requires ships to slowly travel back and forth, scanning the ocean floor with sonar. Unlike satellites that can photograph entire continents from orbit, there is no quick way to map the deep sea in detail.
Another challenge many people overlook is communication. On land, we rely on GPS, mobile networks, and radio signals almost every minute of the day. Underwater, however, these technologies become far less effective. Radio waves travel poorly through seawater, meaning GPS cannot be used to navigate beneath the surface. Instead, the researchers depend on sonar and acoustic signals, which take longer and are less precise. Even operating remotely controlled underwater vessels requires constant adjustments.
Adding to the difficulty is the harsh environment of the deep ocean itself. Beyond the “midnight zone,” the temperatures often hover just above freezing, and the absence of sunlight means plants cannot survive through photosynthesis.
Yet despite these conditions, life continues to thrive. Living in the deep sea requires extraordinary adaptations that are rarely seen anywhere else on Earth. With no sunlight, freezing temperatures and immense pressure, survival depends on evolving traits suited to the harsh environments. Many deep-sea creatures have developed features that are almost alien.
One example is the anglerfish. Living thousands of meters below the surface where food is scarce, the female anglerfish has a glowing lure above its head. Because the deep ocean is extremely cold, animals have much slower metabolisms and need to conserve as much energy as possible, which makes swimming around looking for prey not feasible. Rather than chasing after food, the angler fish waits patiently for prey to swim towards the glowing bulb before capturing it with its powerful jaws.
One of the deep sea’s most misunderstood creatures is the blobfish, often called the “worlds ugliest fish”. However this unusual appearance is actually misleading. Blobfish naturally live at depths of around 600 to 1200 meters where pressure is more than 100 times greater than at sea level. In its natural habitat, the surrounding pressure supports its soft, jelly-like body, allowing it to maintain a more fish-like shape. When brought to the surface, the dramatic drop in pressure causes its body to lose its structure, giving it the droopy appearance that make it famous. Its jelly-like body is actually an adaptation that helps it survive in the deep ocean, allowing it to float just above the seafloor which uses very little energy.
Blobfish at surface level (Image credit: Island Bay Marine Education Centre)
Blobfish in its natural environment (Image credit: National Geographic)
Despite these challenges, one of the most ambitious projects is Seabed 2030, an international initiative launched in 2017 with the goal of creating a complete map of the ocean floor by the year 2030. At the start of the project, only 6% of the global seabed had been mapped to modern standards; since then, the number has grown to roughly one-third of the ocean floor.
Areas shown in shaded blue represent parts of the seafloor considered mapped in the GEBCO 2025 Grid. (Image credit: Seabed 2030)
Exploring the ocean isn’t just about satisfying curiosity. The deep sea plays a vital role in regulating Earth’s climate, storing carbon, producing oxygen through marine ecosystems and supporting countless species. Underwater discoveries can help us lead to new medicines and an understanding of earthquakes, tsunamis and climate change.
The idea that we know more about space than our own oceans may sound surprising, but it shows just how much remains unknown about our planet.
Written By: Grace Lim
Edited By: Sherman Yap
