For thousands of years, the ocean has been the most puzzling region of the planet. Have you ever wondered why it remained so despite the technological advancement in the world?

According to Jacques-Yves Cousteau: "The Sea, once it casts its spell, holds one in its net of wonder forever."

Water bodies make up about 71% of the earth's surface. The vastness of the ocean triggered the interest of many to explore it and dominate it. The idea was to build something that could let them explore the ocean and discover its limits. They started exploring the sea surface, and seeing its wonders, a new question emerged: what lies underneath?

The Vikings were arguably the first to explore the sea’s depth. This is why they are still considered the greatest navigators in history. They attached some sort of weight to a very long rope, allowing it to reach the bottom. They moved it to collect a specimen, and then pulled it back. In that way, they measured the depth of the ocean and also see what was lying underneath. Unfortunately, they weren’t nearly close, but they started a long tradition of exploration that still prevails.

Mystery underneath the ocean

Mystery underneath the ocean

That desire to explore every part of the earth inspired many scientists, philosophers, inventors, and explorers to set sail and reach the unimaginable. In the seventeenth century, a Dutch architect Cornelius Drebbel invented the first submarine. King James I was impressed but didn’t think it could be useful for war, so it was forgotten.

In the following century, French scholar Pierre-Simon Laplace recognized the importance of fully understanding the sea as means of knowledge and power. Laplace successfully calculated the depth of the Atlantic ocean based on the tidal motions from West Africa and Brazil. His calculation: an average of 13,000 ft, was the turning point of the modern sea explorations and has remained the same.

Mystery underneath the ocean

Mystery underneath the ocean

However, British HMS Challenger in 1872 remains the most important sea exploration that has been ever made. It even supersedes the ones that have been conducted nowadays. Within four years of exploration, they discovered 4,417 new marine species, including plants and animals.

At the time, there was the Azoic hypothesis, which states that the deepest regions of the sea were so inhospitable that there was no life existing there.

The HMS Challenger absolutely discredited this theory. A new theory, inspired by Darwin’s evolution theory, was propounded instead. Darwin stated that evolution was a function of the natural selection of small, inherited variations that increased an individual's ability to survive.

Mystery underneath the ocean

Mystery underneath the ocean

They believed the species beneath the ocean have remained the same since the creation of the earth. Their discoveries showed that creatures underneath the ocean evolved and that there was still so much to discover.

Thanks to lots of analysis, scientists have discovered that seabed is not flat but vast and formed by a chain of sea mountains.

According to the National Oceanic and Atmospheric Administration (NOAA), about1 to 5 percent of the seabed has been explored. Why is that?

Mystery underneath the ocean

Mystery underneath the ocean

First, there’s no technology available to go as deep as the ocean is estimated to be. The conditions of these levels are so extreme that it’s impossible to go down there with our current down. Besides that, it is also quite expensive and the international community is more interested in the development of technology on other areas, like space.

As a result, only 556 ft of the seabed have been explored, while about 12,400 ft are still unknown to the human sight.