In 2020, we’re still just getting to know the depths of our home planet. More than 80% of the bottom of the sea is still unmapped and unexplored, according to the National Oceanic and Atmospheric Administration (NOAA).

“We’ve done a pretty good job mapping the surface of the earth and what’s underground. But we have almost no information on what’s really undersea,” explains Dr. Dave Smallwood, program manager in Northrop Grumman’s Mission Systems Sector.

Smallwood has spent his entire career working below the surface of the ocean, and he sees great potential beneath the water. How much of the ocean floor has been discovered so far? By volume, 99% of the Earth’s biosphere remains unknown, according to National Geographic‘s calculations and less than 5% of the seafloor has been surveyed according to NOAA. We actually know much more about the surface of Mars, with NASA reporting that nearly 99% of the planet’s surface has been mapped.

What’s Under the Sea

While you might be picturing smooth, sandy floors, The Atlantic points out that the seabed is actually “a jagged and dynamic landscape” with as much variation as we see on land. Under the depths of the ocean, there are mountains, canyons, hot springs, lakes and hillsides. It’s not just an unknown landscape to explore for the sake of beauty — the deep sea floor contains many minerals that can be useful to us on land.

In addition to minerals, we’ve found unusual animals at the bottom of the ocean. Smithsonian points out that even at 13,000 feet below the surface, where temperatures are near freezing and there’s no sunlight, researchers have discovered living creatures such as fish, coral, crustaceans, jellyfish and worms. With odd looking features such as transparent skin, giant eyes and jagged open mouths, these deep sea creatures look like aliens because they have adapted to their environment. Even in the dark mesopelagic region of 650 to 3,200 feet deep, there are vast potential resources, with gems, metals, minerals, oil and an estimated 10 billion metric tons of marine life, including fish, shrimp and squid, according to the New York Times.

Why We Study the Ocean Floor

One of the biggest reasons to study the bottom of the ocean is fundamental science. There are several business cases for exploring the deepest parts of the sea, but if you don’t have a fundamental understanding of the ocean floor, then you can’t do any advanced work.

Smallwood says, “The contents of the subsea environment at different depths, the physical landscape, what lives there and what doesn’t live there, right, that’s all a priori information for any group that wants to explore.”

Some of the most compelling financial reasons to explore the sea floor are the oil, gas and mineral resources, according to Nature.

“Vast swaths of the open ocean sea floor in the Pacific don’t really fall under anybody’s expanded economic zone or continental claims,” says Smallwood. He adds, “But there are potentially a lot of minerals down there at depths from 4,000 to 6,000 meters.”

That’s why companies are putting large mining equipment under water to harvest raw materials such as rare-earth metals, which are often found in hard to reach places.

There’s also deep water archeology, where scientists study shipwrecks to find evidence of ancient seafaring civilizations. Another subsea industry is aquaculture, the breeding of fish and growing food to feed them, according to NOAA. In other words, it’s farming in the middle of the ocean.

Understanding how much of the ocean floor has been discovered is important for defense. For example, mapping the seafloor is key for naval mine avoidance. The US Navy has been operating beneath the waves in human occupied submarines for over 120 years.

Challenges With Deep Sea Exploration

Clearly, there are many reasons the ocean floor is worth exploring. So why is so much of it still unknown? There are several technical challenges that researchers face when visiting the ocean floor.

First there is the fundamental limitation that humans can’t breathe in water like fish. Even when equipped with SCUBA (Self Contained Underwater Breathing Apparatus) equipment to let them breathe, the pressure of the water (think back to diving in the deep end of the pool and feeling the pressure on your ears) changes the way your central nervous system handles gasses, according to Healthline. Below 100 feet deep, divers can experience nitrogen narcosis, a condition that makes them feel and appear uncomfortably drunk or dazed.

Even if that wasn’t an issue, if you were to go thousands of feet below the surface of the ocean, the pressure is so extreme that it would crush you to death, explains Smallwood. Human-occupied submersibles represent one way to protect and enable humans exploring the deep ocean, but they are expensive and limited in numbers. That’s why, much like with space exploration, most of the deep sea research is done by rovers, unmanned vehicles that explore inhospitable environments.

The ocean’s water itself creates problems because it corrodes the devices that are meant to explore it.

Communication is difficult under water, simply due to the physics of the electromagnetic spectrum. Radio frequency (RF) waves attenuate rapidly under water, so our usual methods of transmitting data are useless.

“You can use them, but what might get you tens of feet or a mile range up on the surface of the earth or in air might get two inches of transmission underwater,” says Smallwood.

Navigation is difficult under the ocean, where there is no GPS to guide the way and minimal known landmarks on the largely unmapped surface. There are alternative methods of navigating, such as inertial navigation, which navigates using the acceleration of your body (or the sensor, robot, or vehicle that is exploring) relative to the Earth.

“It’s an active area of research and development that pushes the bounds of what’s possible,” says Smallwood.

Similarities With Space

The bottom of the sea shares many similarities with space. They are both dark, harsh environments that are difficult and exciting to explore. In space, you have to contend with radiation, extreme temperatures and a lack of gravity.

“Going undersea, you are facing incredibly crushing pressures and a corrosive environment that is trying to eat away at you the minute you touch the water,” says Smallwood.

Both space and the deep sea present engineering challenges, such as power constraints, life support needed for human exploration, and harsh environments that destroy people and equipment. But both environments are bursting with potential. Could the deep ocean be the next frontier?

Smallwood says he considered either a career in space exploration or undersea exploration. He says, “I like the undersea option because it’s much more accessible to me. Within an hour’s drive, I could find somewhere on the water to test, explore, and learn.”