Covering over seventy percent of Earth, the ocean is one of the least explored and understood parts of our planet. In fact, with about 95 percent of its great depths yet uncharted, the mysteries lie here-as big as in outer space. But with the growing level of technological development and curiosity, one may ask a rhetorical question: why is so little known about our oceans, and what secrets might they still hold?

Ocean exploration significantly lags behind due to the huge technical challenge involved in doing so. The deep sea represents a very hostile environment, with crushing pressure and frigid temperatures, in addition to the total darkness outside the photic zone. Reaching such depths requires the use of special equipment like submersibles and ROVs (Remotely Operated Vehicle); hence, such missions are costly and technologically demanding.

Besides, the ocean is a very vast area. Unlike in space, where missions often have certain celestial targets, the ocean floor covers millions of square miles of mostly homogeneous terrain. Such an immense and intricate system would naturally take years of effort, intensive funding, and collaboration among different nations to map out and explore.

Though NASA (National Aeronautics and Space Administration) is now practically synonymous with space travel; it originally started by looking more to Earth sciences, including the study of oceans. Within this earliest era of its existence, the agency studied Earth’s hydrosphere, atmospheric systems, and underwater environments. Some even go so far as to call the shift in NASA’s priorities from ocean exploration to space “mysterious.” The story is certainly exaggerated in some respects, but the shift does reflect a more general pattern over time: public imagination and funding of space over the ocean.

This was for many reasons, some of which are complex to state: the glamor of the stars, the moon race of the Cold War, and then, of course, the potential technological and geopolitical benefits from space exploration lured attention–and resources–away from Earth’s own unexplored frontier.

The mysteries of the ocean are matched only by the speculative wonders of space. Scientists believe that whole ecosystems, geological formations, and even species may remain undiscovered. Hydrothermal vents, first discovered in the 1970s, exposed lifeforms alien-like, living in extreme environments previously considered uninhabitable. What other secrets may the deep harbor?

Then there is that tantalizing prospect of finding historic artifacts and shipwrecks–the ocean floor is essentially a virtual time capsule that can preserve everything from ancient ruins of civilizations to historical events that have occurred at sea. And, of course, there is marine biotechnology. Deep-sea organisms hold partial keys to new medicinal treatments or other sources of renewable energy.

Recently, ocean exploration has gained revived interest. Organizations from NOAA’s (National Oceanic and Atmospheric Administration) Office of Ocean Exploration and Research along with private initiatives, such as that pursued by OceanX, are driving the charge to unlock the ocean’s secrets. On the other hand, improved AI, robotics, and satellite imaging make the efforts of mapping and studying underwater environments much more feasible, but funding for ocean exploration still remains a fraction of what is provided for space programs. This, of course, does bring in a very important question: should we understand the ‘unknowns’ of our own planet before venturing deeper into the cosmos?

The ocean and space are not mutually exclusive frontiers: many of the technologies developed for the exploration of space, including pressurized habitats, robotics, and navigation systems, have direct application in oceanic research. By studying Earth’s deep oceans, we not only gain insights into our own planet but also gather valuable knowledge that could help us explore other worlds, such as the subsurface oceans of Europa or Enceladus.

The ocean is Earth’s last frontier, full of mysteries beneath the waves. Man looks to his space exploration in wonder, yet the depths of his own planet equally hold profound opportunities for discovery and innovation. Perhaps the more humankind continues to stare at the stars, the more it will look inward and unlock the secrets of the world beneath.

And, as NASA’s oceanic origins remind us, the choice between frontiers is not a contest but a convergence. It’s about recognizing that exploration, whether it be into the depths of the sea or horizons of the stars, is a testament to humanity’s unyielding curiosity, a defining trait in its timeless quest to understand its place in the universe.