Ocean Facts: How Much of the Ocean Has Been Explored

Since the ocean is a fascinating place, there are many unbelievable ocean facts that will shock you. It is much bigger than you can imagine, and there are many surprising things you can find.

We’ve chosen only the best information, so if you’re interested to learn more, read on.

Top 10 Ocean Facts to Make You Wonder

How Much of the Ocean Has Been Explored?

Only around 20% of the ocean has been explored as of 2021. Until now, the explorers have been able to map just this much because of the ocean’s size and many drawbacks. But, there are many ongoing expeditions currently mapping the ocean’s bottom with huge success.

(NOAA’s National Ocean Service, 2021)

General Ocean Facts

If you want to learn more about the ocean’s depth, surface, and some ocean animals facts, continue reading.

1. The ocean is, on average, 12,100 feet (2.3 miles) deep.

(NOAA’s National Ocean Service, 2021)

The deepest part of the ocean is 36,200 feet called Challenger Deep, and it’s located at the bottom of the Mariana Trench in the Pacific Ocean.

2. The ocean’s surface covers an area of 139,743,498.65 square miles.

(WorldAtlas, 2020)

When divided into the five oceans, the largest is the Pacific Ocean with an area of 65,144,314.4958 square miles, taking 46.6% of the full surface area. Other oceans are a lot smaller and take up the following areas:

  • Atlantic Ocean 32,870,035.063 sqm — 23.5%
  • Indian Ocean 27,243,368.307 sqm —19.5%
  • Southern Ocean 8,478,803.4016 sqm — 6.1%
  • Arctic Ocean  6,006,977.3826 sqm — 4.3%

Surprisingly, although a lot of this surface is not yet well researched, over 55% of it is already used for industrial fishing.

3. The ocean covers around 70% of the Earth’s surface.

(National Geographic, 2019)

The Ocean is the largest body of water globally, and 97% of the Earth’s water comes from the ocean. Since 71% of the Earth is covered in water, the ocean takes around 70%.

4. 50% of all oxygen comes from the ocean.

(The Conversation, 2021)

Although there’s a misconception that the ocean produces oxygen for humans, this isn’t true. The oxygen produced is ‘consumed’ by animals and other living organisms in the ocean.

But, although this should be enough oxygen for all living creatures, the recent ocean pollution facts and statistics show that there’s a growth of low oxygen patches, where nutrient pollution is preventing life.

5. 3.5% of water’s weight is salt.

(NOAA’s National Ocean Service, 2021)

This number represents the average for the entire ocean. Around the North Pole, South Pole, and the Equator, salt levels are lower. 

The majority of this salt comes from land rock erosion and hydrothermal fluids, which come from vents in the seafloor.

6. There are 372,000 miles of coastline worldwide.

(Medium, 2019, WorldAtlas, 2020)

The largest coastline in the world is in Canada, 125,567 miles long. The US coastline is much smaller and is 12,380 miles long.

7. 3/4 of the ocean is the deep sea ocean.

(Smithsonian Ocean, 2019, Ocean Exploration)

The deep ocean begins at a depth of 650 feet and can be as deep as 36,200 ft — the depth of Challenger Deep.

One of the most interesting deep ocean facts is that there’s no light in the deep ocean, so there’s no photosynthesis, but it’s still full of life, and many creatures live there.

8. Mid-Ocean Ridge is 43,495.98 miles long.

(ScienceDirect, 2020)

Although it’s completely underwater, this is the largest mountain range in the world. It also contains the most active system of volcanoes on Earth.

9. Most animal life can be found in the first 656 ft — the photic area.

(Sciencing, 2019)

This is the only part of the ocean that receives light, and where most of the sea animals live.

One of the most interesting facts about ocean animals is that some don’t live in this area because of the light but because of the planktons. Zooplanktons need light, and animals like fish and even whale sharks feed on zooplanktons.

Ocean Exploration Facts and Important Discoveries

The ocean has been explored for a long time, and although we’ve just scratched the surface, many things have been discovered. Our ocean stats and facts will show you the history of ocean exploration, important explorations, and discoveries. 

So, let’s dive in.

10. First ocean explorations started around 4500 BC.

(Sea and Sky, 2020)

This was when early and primitive ocean exploration started, but diving was mainly used to find food.

Look at our ocean exploration timeline to learn more about this surprising and fascinating history.

  • 900 AD — Vikings start exploring the ocean through their travels
  • The 1400s/1500s — great open ocean exploration trips (Columbo, Magellan, etc.)
  • 1620 — first submarine invented
  • 1797 — first diving suit
  • 1800  — the invention of Nautilus (famous submarine)
  • 1849 — Continental Shelf discovery
  • 1867 — confirmation of the deep-sea life
  • 1872 — 30,000 ocean species discovered, H.M.S. Challenger exploration
  • 1899 — Pacific expedition
  • 1925 — mapping the Ocean Floor
  • 1934 — first deep dive expedition
  • 1950–today — golden age (Mariana Trench discovery, marine laboratories, ocean surface, and ocean floor mapping from space, expeditions to the Challenger Deep)

11. 240,248 different ocean species have been discovered and cataloged.

(World Register of Marine Species, 2022)

This number is accurate at the time of writing but is changing daily and the number is updated regularly. 

There are no specific numbers that show how many different species actually live in the ocean. But, since the ocean biome is one of the richest and is home to many animals and other living creatures, the numbers could be in millions. 

Although the numbers can only grow, as scientists discover new species, ocean statistics show that many ocean animals, like Hector’s dolphin, are near extinction.

12. Only around 20% of the ocean floor has been mapped.

(GEBCO Seabed 2030 Project, 2020)

In 2017, only 6% was mapped. But the 2020 ocean floor exploration facts show that the number is now much higher. 

Using the newest ocean exploration technology, a group of scientists has been exploring the ocean floor and has mapped 5.6 million sqm in just one year. They plan to finish mapping the other 80% by 2030.

13. One man reached the five deepest points in the ocean in 2019.

(Guinness World Records, 2020)

Victor Vescovo went to:

  • Molloy Deep —  18,212 ft
  • Java Trench —  23,596 ft
  • South Sandwich Trench —  24,390 ft
  • Puerto Rico Trench —  27,480 ft
  • Challenger Deep (deepest point on Earth) —  35,843 ft

This is officially the deepest ocean exploration by a crewed vessel to date. 

The record for the deepest solo dive was previously held by the famous film director James Cameron. James Cameron’s ocean exploration was in 2012, but he didn’t go as deep as Vescovo.

14. Ocean explorations can bring new sources for medical therapies.

(NOAA’s National Ocean Service, 2021)

The ocean is a source of ingredients for many new antibiotics and antiviral medicines. These discoveries can be crucial for curing certain diseases.

Other ocean exploration benefits are the following:

  • Development of new technologies and scientific processes
  • Helps sustainable ocean management
  • Shows the impact of environmental changes
  • Useful for national security, country boundaries, and using ocean resources

Fun Facts About the Ocean

For all the ocean enthusiasts, we’ve prepared some interesting facts about the ocean that will surprise you. We’ve also found some terrifying and creepy facts about the ocean to make you shiver.

So, be sure to continue reading.

15. Hydrothermal vent water can reach 700°F.

(NOAA’s National Ocean Service, 2021)

This means it could easily melt you! 

But, even though it’s this hot, the water in hydrothermal vents doesn’t boil due to the pressure. And interestingly, the space near these vents is home to various living beings.

Hydrothermal vents are the ocean’s hot springs produced by underwater volcanoes. They were first discovered in 1977 near Galapagos and are still interesting to scientists.

16. A mammoth tusk was found in the ocean in a 2021 expedition.

(Mashable, 2021)

The tusk, which belonged to a Columbian mammoth, was found 10,000 feet below the ocean surface during a deep ocean exploration using a robot.

The scientists are not sure how it got there, but it probably got washed into the ocean during a larger flood.

17. The pressure 300 feet deep in the ocean is 10 atmospheres.

(The Atlantic, 2020)

And it becomes worse if you go deeper. This is one of the scariest facts about the ocean since this means that the ocean can crush you! 

The pressure is 100–300 times higher than the one in car tires. This is why deep ocean exploration and research without special pressure-proof equipment is impossible.

Animals living in the ocean are adapted to the high pressure, and their bodies are specifically made to live there. For example, whales have more flexible cartilage, allowing their lungs not to rupture and their bones not to break.

18. The first ocean appeared around 4.4 billion years ago.

(Smithsonian Ocean, 2019)

The year is based on the ocean data that scientists currently have but is only approximate. 

Of all the now known oceans, the Pacific was the first one to form — 200+ million years ago, and was named in the 16th century by the explorer Ferdinand Magellan.

19. By the end of the 21st century, the ocean might change its color. 

(Nature, 2019)

These changes in the ocean color come from pollution and climate change, which impact phytoplanktons. With fewer phytoplanktons in the water, the colors become more intense.  

Although phytoplanktons aren’t responsible for the blue color, they’re directly responsible for the hue.

Satellites have already observed the changes, suggesting that life is starting to die in some ocean parts. 


Why did NASA stop exploring the ocean?

NASA didn’t actually stop exploring the ocean. But, NASA’s ocean exploration is not as you would expect it to be. They only explore the ocean from their satellites. 

Although some internet sources claim that NASA was initially created to explore the ocean, and after a mysterious discovery switched to space, this was proven to be a lie. NASA has always been a space and atmosphere research agency.

(The Focus)

Have we been to the bottom of the ocean?

Yes, humans have reached the bottom of the ocean. Even the deepest part of the ocean was explored a few times.

But, some parts of the ocean bottom still remain a complete mystery to us, and aren’t yet researched.

(Live Science, 2020)

What is unique about the ocean?

What makes the ocean unique is that it’s the place where most life on Earth happens, but we know so little about it. 

And, if you read all of our facts about the ocean, you’ll see how unique and special it is.

(NOAA’s National Ocean Service, 2021)

What has been discovered in the ocean in 2021?

The most exciting discovery is the mammoth tusk found 10,000 feet deep in the ocean. Other explorations and discoveries are the following:

  • Scientists have explored life 13,000 feet below the ice in the Arctic ocean.
  • Potentially new, unidentified life forms were found near a hydrothermal vent.
  • The barrels of waste were found near the Los Angeles coast.
  • A new species of glowing sharks was observed.

(Mashable, 2021)

Why is 80% of the ocean undiscovered?

Firstly, it’s undiscovered because it’s not accessible due to the high pressure and darkness.

But, the biggest reason is that humans simply didn’t have the means to explore it until recently. Now, with new technology and ocean robots, the situation is changing.

Usually, people compare ocean exploration vs. space exploration and wonder how we can observe everything in the universe but not in the ocean.

The reason is light in space and excellent telescope power. But in the end, we have researched 20% of the ocean, while we still don’t know much about the universe at all.

(Oceana, 2020)


The ocean is a place of wonder, which has puzzled people from the beginning of time. It takes up around 70% of our planet, but we know so little about it. 

But, we’re starting to know it a bit better with all the new research. This is why we chose the best and most recent ocean facts to help you understand it a little bit and appreciate how great it is.


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