It's actually funny when you think about it. A living species that is capable of creating technology that has left the solar system and is in interstellar space, should also know everything about its own planet. But the truth is far from it. According to reports, only about 5% of Earth’s ocean floor has been mapped. We’ve mapped Mercury for crying out loud! Yet 65% of Earth’s crust remains unmapped.
It's not that the ocean floor can’t be explored. There are a lot of reasons why the ocean floor is unmapped and oceanic exploration has remained a nascent subject. The number one reason why ocean exploration has remained insignificant is because of the emergence of space travel. The sheer excitement and hype towards space travel just undermines oceanic exploration. The Cold War era added to this hype and the Space Race just ensured that people look towards the sky and not to the abyss below them (EHEHE! Metaphors). This social conditioning has deprived oceanic exploration of having a WOW factor and prevents people from taking interest in the subject.
Since oceanic exploration can’t be privately handled due to international laws and expenses, governments are responsible for it. For example, U.S.A. has the NOAA(National Oceanic and Atmospheric Administration). These organizations don’t get the necessary funding and they have a very tough time innovating with negligent funding.
The second reason is that ocean exploration is expensive and, if it's seriously considered, it’s expenses might even be more than space travel. Space travel is technically easier. There are set laws to it that rarely change and a satellite millions of miles away follows the same rules as a satellite just outside the atmosphere. In the ocean, nothing is consistent. The biggest danger to oceanic exploration is water itself. The atmospheric pressure increases for every 10 meters, so after a certain depth, submarines can literally get crushed. The depth also makes satellite imaging nearly impossible though new technology is being developed to counter this. The existence of living organisms, currents and underwater volcanoes change the tech requirement and the lack of funding prevents creation of new tech.
A Personal submarine
Let’s hope someone popularizes ocean exploration the same way space exploration has been popularised.
The ocean floor remains one of the most underexplored places known to humans. Only about 5% of the ocean floor has been topographically imaged. Unlike the space and other planets, the ocean floor cannot be mapped using radar because the ocean water tends to obstruct a satellite’s radio waves. The deepest point ever reached by humans is 35,858 feet below the surface of the ocean.
Also, getting humans to go down the deepest part of the ocean is extremely difficult because of the pressure down there. Keep in mind that for every 10 meters increase into the water, there is an additional atmosphere of pressure. The pressure makes it difficult and dangerous for the ocean floor to be explored.