How much of the ocean has been explored? Surprisingly little

Better yet, we have even successfully located some of their mysterious underwater structures, such as the 7-mile-deep Mariana Trench, Earth's deepest locality, and the Bermuda triangle. And let's remember the discoveries of whole submerged cities, such as the 5000-year-old Palvopetri in Greece, which may have been submerged around 1,000 BC.

Still, despite our best efforts, the scale of the oceans and what lies within them continues to be somewhat incomprehensible. In truth, we might already be more familiar with the universe than our oceans; "We have better maps of the surface of Mars and the moon than we do of the bottom of the ocean," said NASA's oceanographer Dr. Gene Feldman.

In this article, Interesting Engineering (IE) explains just how much of the oceans we have explored.

How many oceans are there?

Our Earth is unique in the solar system. Its optimal distance from the Sun and the predominance of liquid on its surface and atmosphere contribute to this.

Over 70 percent of the Earth's surface lies below a large saltwater body- the global ocean. However, scientists have categorically divided the body of water into four major oceans; the Great Pacific, Atlantic, Indian, and Arctic. And as of recently, there is now a fifth!

On June 8, 2021, National Geographic, which has been making maps since 1915, recognized a fifth ocean called the Southern Ocean, which encircles Antarctica.

All oceans collectively contain an estimated 97 percent of the world's water.

How much of the ocean has been explored?

Despite modern technologies, only 5 percent of the oceans have been explored. As such, the remaining 95 percent remains untouched, unseen, and undiscovered to date.

Marine life

Regarding marine species, scientists have yet to discover how many exist in the oceans. Currently, around 226,000 ocean species are known. Some believe many ocean species are declining due to marine ecosystems suffering from rising sea temperatures, pollution, and other issues.

That said, scientists are always finding new living species, and it is estimated that a few hundred thousand to a few million more species are yet to be discovered.

Better yet, over the last decades, oceans have been an incredible source of information about the evolution of the animal kingdom. From the largest shark to ever live - the prehistoric megalodon - to the modern tubeworms of the extreme, deep-sea environment, ocean exploration has revealed that life on Earth has changed remarkably since it first began evolving.

Ancient civilizations

Ocean exploration has also been key to uncovering significant ancient human secrets. For instance, the Antikythera mechanism, which could be the world's first computer and was created in 100 BC (2,122 years ago), was found in a shipwreck in 1901.

Plenty of ancient civilizations whose cities now lie underwater have also been explored, such as Palvopetri in Greece. At 5000 years old, this submerged city is considered the oldest of its kind on Earth. For thousands of years, the town was buried right beneath our eyes until a young oceanographer found its walls just three to four meters below the sea's surface.

A history of ocean exploration

The study of all aspects of oceans is termed oceanography. Modern oceanography is one of the more recent additions to scientific disciplines. Still, its roots can be traced back tens of thousands of years to when people first started traveling out to sea in rafts and exploring their coastlines.

6022 years ago (c. 4000 BC)- first sailing vessels

In ancient Egypt, close to the mouth of the Nile River, some of the earliest sailing ships were probably made solely for travel in the Mediterranean Sea.

In fact, a discovery in 1994 of a ceramic shard dating to c. 3000 BC (c.5,022 years ago), suggests the ocean was already being traversed for trade between ancient Egypt and Greece. The shard was revealed to be a fragment of a wine jar exported from the Nile Valley to Palestine. Since the wine was almost impossible to produce in the Egyptian climate, it probably came from Greece - indicating trade links between Greece and Egypt.

2,922 years ago (c. 900 BC) - The first sea routes

The ancient Phoenicians- an ancient civilization of the eastern Mediterranean - were skilled navigators who pioneered sea routes around the Red Sea and the Mediterranean and may have traveled the Indian Ocean as well.

Some believe that these early mariners may have traveled as far as England.

Around 900 AD – Viking ocean exploration

Vikings began measuring sea depth around the eighth century by throwing lead weights attached to ropes overboard. They'd then note how much of the rope was submerged when the weight hit bottom.

As masterful ocean navigators, the Vikings were among the first explorers to use the North Star to keep their course while at sea. This expertise enabled them to travel and colonize many territories, including Newfoundland, Greenland, and Iceland.

As highlighted in a previous IE story, tree rings and astrophysics suggest Vikings beat Christoper Columbus (discussed below) to the discovery of North America by around 500 years.

Late 1400s-1500s

Explorer Christopher Columbus (1451–1506) and his crew made four trips across the Atlantic Ocean from Spain: in 1492, 1493, 1498, and 1502. Guided by the view that the Earth is round, Columbus argued that he could sail west to reach "the east" (India and China). Of course, we all know he stumbled across the Americas instead.

Furthermore, in 1519 Ferdinand Magellan and his crew set out from Portugal on a perilous journey that would eventually lead to the first circumnavigation of the globe. Although, as IE previously highlighted, when Megallan achieved this is under debate.

Modern Oceanography - from the late 19th century

Modern oceanography emerged as a scientific discipline less than 130 years ago- in the late nineteenth century, several expeditions launched by Americans, Britians, and Europeans enabled the exploration of ocean currents, ecosystems, and the seafloor off their coasts.

For instance, the Challenger expedition, which took place from 1872 to 1876 aboard the British three-masted HMS Challenger, was the first to collect information on ocean temperatures, chemistry, currents, life, and seafloor geology.

Later, in 1951, the HMS Challenger II used sonar to discover the ocean's deepest point (10,929 meters) in the Mariana Trench, the Pacific Ocean. This came to be known as the 'Challenger deep.'

Almost 150 years after the first Challenger expedition, another expedition called the "Five Deeps", visited the deepest point in each of the Earth’s five oceans.

The other four 'deeps' were the Puerto Rico Trench in the Atlantic Ocean (27,480 feet/8,376 meters), South Sandwich Trench in the Southern Ocean (24,390 feet/7,434 meters), Java Trench in the Indian Ocean (23,917 feet/7,290 meters), and Molloy Deep in the Arctic Ocean (18,284 feet/5,573 meters).

After the Titanic sank in 1912, technological efforts to solve problems of early warning of underwater obstructions were made to prevent such a tragedy from reoccurring. One of which was Reginald A. Fessenden's 1914 'Fessenden Oscillator,' which could detect underwater objects by bouncing sound waves between the objects and the sea floor.

This invention could also be used to detect the depth of the ocean. Additionally, it paved the way for creating what we know today as sonar.

1995- Mapping the seafloor from space

Geosat satellite radar altimetry data lead to detailed worldwide mapping of the sea floor from space.

2017 – Mapping global ocean depth

Seabed 2030 is a new international initiative to gather all available bathymetric (underwater depth) data and make a definitive, publically-available map of the world's ocean floor by 2030.

How deep is the ocean?

Even though there is still much to discover, oceanographers have made some incredible findings. For instance, we are aware that, like on land, the ocean is home to trenches and towering mountain ranges.

If Mount Everest, which stands 8.84 kilometers (5.49 miles) tall, were placed in the Mariana or Philippine Trenches of the Pacific Ocean, two of the ocean's deepest regions, its peak would not even touch the surface of the water.

Conversely, the Atlantic Ocean is comparatively shallow because a large portion of its seafloor is made up of continental shelves, which are portions of the continents that extend far out into the ocean. The overall average ocean depth is 2.3 miles (3,720 meters).

Why is it complicated to explore the ocean?

You're probably wondering why only 95 percent of the ocean has been explored.

There is no doubt that satellites can map the ocean's surface temperatures, waters, turbidity, color, etc. Still, we need far more technological advances, such as deep sea submarines and sonars, to map its deeper parts. In addition, deep water makes it difficult to see.

Extreme exploration conditions at great depths contribute to the relatively small percentage of the ocean explored. The "sunlight zone" ends about 200 meters beneath the surface, making imaging much more complex. Additionally, the pressure at depth is exceptionally high, increasing about one atmosphere for every 10 meters of water depth. At a depth of 5,000 meters, the pressure is around 500 atmospheres or 500 times greater than the pressure at sea level.

The good news is that scientists are developing a range of undersea exploration vehicles, including 'biorobots' that can explore the depths difficult for humans to reach.

Why did NASA stop exploring the ocean?

Though there are many rumors about NASA exploring oceans in the beginning and then suddenly quitting it - there is no real evidence for this.

Since 1958 to now (2022), NASA's primary objective has been air and space exploration. However, NASA does assist various other organizations that work solely to examine and survey the oceans, such as the United States National Oceanic and Atmospheric Administration (NOAA).

Further, several viral TikTok videos have led to several conspiracy theories, including one that described NASA as dropping out of ocean exploration due to discovering a somewhat deadly 'massive unknown species.' Apparently, it was so horrific that NASA started researching outer space to try and get humans off Earth.

someone told me NASA was first created for deep ocean exploration and then immediately changed to space exploration for no reason and i thought that was the scariest thing ever until i searched it up and it isn’t true ??

— Bryan (@bryrosaa) April 3, 2021

Still, as interesting as the story may sound, it's just that- a story.

The truth is that as ocean exploration technology develops, the amount of knowledge yet to be discovered is as vast as the immenseness of the oceans.