25 Mind-Boggling Facts About the Ocean You May Not Already Know

The ocean covers more than 70 percent of the Earth’s surface. Considering how vast it is, scientists know relatively little about what’s going on down there. On top of that, there are many popular myths that have muddied the waters, making sorting fact from fiction a challenge.

Did you know the oceans provide half of Earth’s oxygen? Or that the oceans absorb about 30 percent of human-made carbon dioxide? They also store excess heat energy. All of these facts make them a vital part of our biodiversity.

Here are some more facts about the ocean to wrap your head around. Some you may already know, but others might just blow your mind.

1. There’s not that much salt in the ocean.

Only around 3.5 percent of it is salt. So what makes the ocean taste so salty? The ocean has two main sources of salt: runoff from the land and vents on the seafloor. The runoff from land is the result of rain, which is slightly acidic, eroding rocks. The eroded rock material contains ions that wash into streams, rivers and finally into the ocean. The other source of salt is mineral-rich hydrothermal fluids that come from vents on the seafloor.

2. The oceans contain 97 percent of the planet’s water.

The ocean basins are so vast and deep that they hold about 97 percent of the Earth’s water. Sea water that’s trapped in glaciers and ice caps accounts for another two percent. Do the math: That means that less than one percent of the Earth’s water is fresh.

3. Most of the oceans’ wildlife has yet to be discovered.

Scientists don’t know how many species live in the oceans, but they estimate that 91 percent of them have yet to be classified.

4. Oceans help keep the Earth cool.

The oceans absorb about 91 percent of the excess heat that is trapped by greenhouse gases.

5. The oceans are largely unexplored.

Less than 10 percent of the world’s oceans have been documented or explored. There is a project currently underway called Seabed 2030 that intends to map the entire seabed by the year 2030, allowing us to better understand our oceans in the future.

6. Our coral reefs are on a doomsday path.

Since 2009, rising sea temperatures have destroyed around 14 percent of our coral reefs. If temperatures continue to rise at their current rate, we could lose 70-90 percent of all coral reefs by 2050 or sooner.

7. There are more than 500 species of sharks.

Of course you know all about the great white shark, and you can probably easily come up with several other species names as well, but did you know there are over 500 different types of sharks that live in the oceans? And the size range is enormous: the largest species (the whale shark) is 40 feet long, whereas the smallest species (the dwarf lanternshark) is only 7.9 inches long.

8. There is a shark that can walk. (Yes, really!)

The epaulette shark can swim—but it can also “walk” along the ocean floor as well as over shallow reefs that may even be exposed to air. It uses its pectoral fins to create a crawling motion to propel itself across reef systems. As far as air exposure, the epaulette can slow its heart rate and breath so it can survive without oxygen for an extended period of time.

9. The deepest point in the ocean is really, really deep.

The Challenger Deep in the Mariana Trench, located off the east coast of the Philippines, is the deepest part of the ocean. At 35,876 feet below sea level, you could comfortably fit Mt. Everest in there, with room to spare.

10. The Pacific Ocean was named by Ferdinand Magellan.

In the 16th century, Portuguese explorer Ferdinand Magellan set sail on behalf of the Spanish Empire to search for a new route to the Spice Islands. When he and his crew entered an unfamiliar sea in November of 1520, he called it pacific, meaning peaceful.

11. The world’s longest mountain range is in the ocean.

The Mid-Ocean Ridge is a mountain range that stretches for 40,390 miles. More than 90 percent of it is underwater, but parts of it jut above water in the form of volcanic islands, including Iceland and the Azores.

12. The ocean is the world’s largest museum.

There are more artifacts and pieces of history on the ocean floor than there are combined across all the museums of the world. Examples of these artifacts include sunken objects and shipwrecks as well as fossilized records of various animal species.

13. The warmest ocean is like a relaxing bath.

The Indian Ocean can range from 72°F to 82°F, meaning you’re not going to need a wetsuit there. A large portion of the Indian Ocean is in the tropics, near the equator, which means this ocean is exposed to more sunlight.

14. The coldest ocean is like an ice bath.

The Arctic Ocean can feel like taking an ice bath. The average water temperature hovers around the 28°F mark, which is what you would expect from an ocean that hugs the North Pole and is covered with sea ice for most of the year.

15. The Atlantic was named after a Greek Titan.

The Atlantic gets its name from the Greek mythological god Atlas, who was condemned by Zeus to hold up the heavens on his shoulders. The name is meant to reflect the immense size of the Atlantic, which covers approximately 20 percent of the Earth’s surface.

16. The largest ocean could fit all the continents combined.

The Pacific Ocean is more than 60 million square miles. It’s so big, you could fit the United States (including Alaska and Hawaii) in it 15 times over with room to spare. Here’s another mind-bender: You could fit all of the Earth’s continents inside the Pacific a bit of wiggle room leftover.

17. The smallest ocean is still pretty big.

The Arctic Ocean is the world’s smallest ocean, but it’s still pretty massive at 5.4 million square miles. You could fit Australia in there 1.8 times!

18. The moon and the oceans are connected.

The gravitational forces of the moon are responsible for tides. The oceans on the side of the Earth that is facing the moon are pulled, creating a bulge. Meanwhile, on the opposite side of the planet, a second bulge forms as a result of the weaker lunar gravity as well as the inertia of the water in relation to the Earth’s rotation. Low tides occur in the areas between the two bulges. Each day, there are two high tides and two low tides.

19. The youngest ocean is the Atlantic.

The Atlantic Ocean was formed about 150 million years ago, during the Jurassic period, when the supercontinent Pangaea began to separate.

20. The oldest ocean is the Pacific.

The Pacific contains the world’s oldest ocean basin, and the oldest rocks there have been dated to 200 million years old. The Mediterranean Sea, however, may contain the world’s oldest piece of ocean crust, which has been dated to an astonishing 340 million years old.

21. The oceans are actually a single body of water.

Though different parts of it have different names, the ocean is actually one global body of water, separated only by geographic, cultural and historical boundaries. Despite long-standing myths, the Pacific and Atlantic ocean do mix their waters—but they each retain their own unique characteristics.

22. The oceans have a midnight zone.

The name sounds kind of terrifying, but the midnight zone simply refers to areas of the oceans that are so deep that sunlight cannot penetrate. Also known as the bathypelagic zone, this layer of ocean occurs between 1,000 to 4,000 meters (3,300 to 13,100 feet).

23. The oceans also have an abyssal zone.

Below the midnight zone is the abyssal zone; this layer occurs between 4,000 and 6,000 meters (13,100–19,700 feet). This zone is just as dark as the midnight zone, but it is colder and higher-pressure.

24. Marine snow is kind of gross.

The deep ocean floor is covered in marine snow. Though the name sounds romantic, it is actually a continuous underwater shower of decaying organisms, fecal matter and any other debris that’s made its way to the bottom of the ocean. The material serves as the primary food source for many animals and organisms that live in the deep ocean.

25. Some dolphins like to get high.

The BBC documentary Spy in the Pod (2024) shows footage of dolphins gently nudging pufferfish with their noses, causing the puffers to release their neurotoxins. In small doses, these neurotoxins can induce a trancelike state, and these dolphins seem to know exactly what they’re doing. Niiiice.

This story was originally reported by Surfer on Sep 6, 2025, where it first appeared in the News section. Add Surfer as a Preferred Source by clicking here.

25 Mind-Boggling Facts About the Ocean You May Not Already Know

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