Unexplored

Oceans cover more than 70 percent of Earth’s surface, however approximately only five percent of the ocean has been discovered, which leaves 95 of the ocean unexplored. The oceans remain one of the most underexplored places known to humans and we actually know more about the topography of Mars than we do about the Earth’s seafloor. The main reasons are pressure and darkness. It’s dark down there at the bottom of the sea, much darker than you might be able to imagine, because the ocean is very, very deep, thus light has a hard time being able to penetrate the deepest depts of the ocean. This is because as the light energy travels through the water, the molecules in the water scatter and absorb it.

In a gravitational field, such as on the surface of Earth, everything is accelerated downward by the Earth’s gravity, giving it weight. At any depth in the ocean, the weight of the water above pushes on any object below it. With every foot an object descends into the ocean, more water is pushing down and against it, and more pressure is exerted upon that object. If you are at sea level, each square inch of your surface is subjected to a force of 14.6 pounds. The pressure (force per unit area) increases about one atmosphere for every 10 meters or 32.8 feet of water depth. At a depth of 5,000 meters the pressure will approximately be 500 atmospheres or 500 times greater than the pressure at sea level. Most of the deep ocean is under pressures of 3000 to 9000 pounds per square inch (or about the equivalent of 100 to 300 times the air pressure in automobile tires). At the bottom of the Mariana trench (deepest part of the ocean being 10,994 meters or 36,070 feet below sea level) the water column above exerts a pressure of 1,086 bars (15,750 psi), more than 1,000 times the standard atmospheric pressure at sea level.

Humans are always under a certain amount of pressure, but we just don’t notice it. The Weather Channel tells us the forecast, weather conditions and Doppler radar and the air pressure, which changes as air warms, it rises and leads to low pressure on the surface, and as air cools, it falls resulting in high pressure on the surface, but we actually have our own pressure in air-filled spaces of our body like our lungs, stomach, and ears. Our internal pressure is usually equal to the outside air pressure (the weight of the atmosphere pushing down on us.) We become uncomfortable whenever we venture away from sea level, as this results in our internal pressure no longer being equal to the ambient pressure. This is why our ears hurt when we go up in a plane or when we dive too deep underwater.

We can’t just create extra-long snorkels to breathe underwater, because for every 33 feet a diver descends the weight of the water above them increases by 15 pounds per square inch. At only a few feet below the surface, the water pressure is already too great for the muscles that expand and contract our lungs to work, making it extremely difficult for us to draw breath. A couple feet of water pressure isn’t enough to do serious damage yet, but looking at deeper levels shows how pressure affects us a little more gradually. In 1973, without a breathing apparatus a Frenchman, Jacques Mayol was able to dive down 86 m or 282 feet. Scientists haven’t yet determined a hard limit for how deep we can survive underwater. Most professional free divers don’t go past 400 feet deep.

Technically, most of the ocean floor has already been mapped, but at a mere resolution of five kilometers, which at best shows a rough approximation of undersea trenches and seamounts. Compared to NASA’s unprecedented 20 meter resolution Martian maps, almost everything produced by bathymetry is seemingly light years behind. The shape of the ocean floor helps determine weather patterns, detect when and where tsunamis will strike and aides management of fisheries that feed millions. Studying the length and height of the ripples revealed at the bottom of the oceans can give clues to the effects of past storms, and hopefully help us to predict the effects of future storms. When storms travel over water, their waves create movement on the ocean floor, formations called ripple bedforms. The theories go that the larger the distance of the waves, the larger the distance of the ripples. These ripples create a fingerprint or signature of storms past. In 2017, an international team of experts from around the world, united under the non-profit General Bathymetric Chart of the Oceans (Gebco), launched the first effort to create a comprehensive map of the world’s oceans.