12 Amazing Ocean Facts

The ocean is a vast, beautiful and mysterious place. In this article, you can learn some fun facts about the ocean and its inhabitants. 

Earth from Space
Earth from Space. H. Armstrong Roberts/ClassicStock/Archive Photos/Getty Images

When you hear about the ocean, you usually hear it referenced not as "the ocean" but with a more specific name, like Atlantic Ocean, Pacific Ocean or the Indian Ocean.  There are five defined oceans around the world. In order of size, they are  the Pacific, the Atlantic, the Indian, the Southern (Antarctic), and Arctic Oceans. But in fact, they are all connected, so there is really one ocean on Earth. More »

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The Ocean Covers 140 Million Square Miles.

Scenic View Of Sea Against Clear Blue Sky
The Vast Ocean. Jens Mayer / EyeEm / Getty Images

Earth is often called the Blue Planet because so much of our planet is ocean. The ocean covers 71% of the Earth's surface, which amounts to 140 million square miles in area.  As far as volume, the amount of water in the ocean is about 330 million cubic miles.  

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The Ocean Contains 97% of the Water on Earth.

Infographic of water cycle
Infographic of water cycle. Michele Rosenthal / Getty Images

One of the unique things about Earth as a planet is its abundance of water. If you've ever studied the water cycle in school, you know the ocean is an important part of this process. One reason is that the ocean contains 97% of Earth's water.  Because of its large size, the ocean affects climate and even reduces the carbon dioxide in the atmosphere by absorbing carbon. 

So, if 97% of the water is in the ocean, where is the rest? Ice sheets and glaciers contain about 2% of Earth's water, and groundwater, lakes, rivers, soil and the atmosphere each contains a fraction of 1% of the water on Earth. 

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The Ocean Provides Half of the Air You Breathe.

Phytoplankton Image, Courtesy NOAA
Phytoplankton. NOAA

Terrestrial plants do photosynthesis, which provides oxygen for humans and other animals.  Phytoplankton, or plant-like plankton, also do photosynthesis. The ocean is so huge and full of so much plankton that it has been estimated that, through photosynthesis, phytoplankton are responsible for 50 to 90% of the air that we breathe here on Earth. So, a great incentive to keep the ocean healthy is because it helps us breathe.

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The Ocean Bottom Isn't Flat.

Diver on wall. Underwater features like this show how the ocean bottom isn't always flat.
Diver on wall. Underwater features like this show how the ocean bottom isn't always flat. Stephen Frink / Getty Images

If you wade into the ocean from the beach, you'll likely encounter a mostly flat bottom. While some of the ocean is flat and covered with sand, if you walked across the Atlantic Ocean, for example, you'd encounter dramatic differences in water depth and bottom types. 

Walking across the floor of the Atlantic Ocean, you'd encounter hills, valleys and even mountain ranges. In fact, you'd have to cross the longest mountain range in the world, the mid-ocean ridge, which extends like a baseball seam more than 40,000 miles around the Earth. Oddly enough, we've explored more of the Moon, Venus and Mars than of the mid-ocean ridge.

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The Deepest Point in the Ocean is over 36,000 feet.

Deep sea anglerfish (Linophryne arborifera)
Deep sea anglerfish (Linophryne arborifera). Peter David/The Image Bank/Getty Images

Most of us are most familiar with shallow ocean waters near shore.  Even the area where I see whales in the summer is only a few hundred feet deep.  Overall, the average ocean depth is about 2.4 miles, which is pretty deep. But it gets much deeper than that. 

The deepest point in the ocean is called the Mariana Trench, which lies over 36,000 feet (more than 7 miles) below the ocean surface. Although most of the deep ocean has not been explored, humans have made it into the Mariana Trench and to the Challenger Deep, which is the deepest spot in the ocean. We don't fully understand how many creatures can survive in this environment, but we know some can - there are at least some protists, microorganisms, bacteria, amphipods and possibly even some fish that can live in this challenging environment. 

As more of the ocean gets explored, we'll likely learn that even more marine creatures have adapted to live in this deep sea world. 

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Water Pressure in the Ocean Can Be as Much as 16,500 Pounds Per Square Inch.

Styrofoam cups compressed by water pressure.
Styrofoam cups compressed by water pressure. NOAA's National Ocean Service, Flickr

On Earth, we endure pressure from the weight of the atmosphere. We don't feel it, but that pressure amounts to about 15 pounds per square inch. This is known as one atmosphere. In a normal situation, we don't feel the pressure because our internal pressure is equal to the external pressure. We only feel it if we dive too deep or go up too high (e.g., on a mountain or in an airplane).

If you've done any scuba diving, you know that the water pressure in the ocean increases with increasing depth. In the ocean, the water pressure increases by 1 atmosphere every 33 feet (or about every 10 meters).  So that means every 33 feet you go down into the ocean, you're increasing water by the pressure of the entire atmosphere.

About 3,280 feet (1,000 meters) down, the water pressure is 1,500 pounds per square inch. In the Mariana Trench, the water pressure is about 16,500 pounds per square inch!

Because our bodies have spaces filled with air, we are limited as to the water depth we can stand. Most humans can scuba dive to about 131 feet deep without the use of special equipment. Professional free divers have descended several hundred feet. Water pressure compresses our lungs and at deep depths, makes it impossible to breathe.

Ocean animals are limited by depth as well. Shallow water ocean animals, like fish with air bladders, couldn't survive at deep water depths, as their air bladders would be crushed by the immense pressure. Animals that live in the deep sea have bodies that are mostly liquid that is incompressible. When brought to the surface, these animals may survive, but may suffer neurological impairment or other damage.

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Ocean Temperatures Can Be From 28 to 750 degrees.

Active Hydrothermal Vent Image / Image courtesy of Submarine Ring of Fire 2006 Exploration, NOAA Vents Program
An active hydrothermal vent chimney spewing out hydrothermal fluids. Ring of Fire 2006 Expedition. East Diamante Volcano, April 29, 2006. Image courtesy of Submarine Ring of Fire 2006 Exploration, NOAA Vents Program

The ocean water coming from hydrothermal vents can be 750 degrees Fahrenheit.  However, around deep sea vents, the waters can also be very cold - just above freezing.

The coldest waters, as you would probably guess, are near the poles, where the water temperature can be 28 degrees Fahrenheit. Amazingly enough, icefish survive in this challenging habitat because their bodies are equipped with antifreeze proteins.

Colorful Coral Reef, Similan Islands, Thailand
Colorful Coral Reef, Similan Islands, Thailand. kampee patisena/Moment/Getty Images

Many people like to visit the Caribbean, where water is clear and blue. This water clarity makes for great snorkeling and scuba diving. However, colder waters have less visibility and an almost murky appearance. In cold waters like those in the North Atlantic Ocean, visibility is low due to the presence of plankton and other organic matter in the water column. The water also tends to be greenish due to the phytoplankton in the water column.  

In tropical regions, the plankton and productivity are located on and around reefs. This means there is less material suspended in the water column in these regions and the water is a beautiful, clear blue.  More »

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The Biggest Ocean Animals Stretch More Than 100 Feet.

Blue Whale / Fotosearch / Getty Images
Blue Whale. Fotosearch / Getty Images

The biggest animal in the world is the blue whale.  The blue whale is an immense creature that is longer than 2 school buses and weighs more than 25 elephants put together.  They are found in oceans around the world. These gigantic animals eat small krill and zooplankton, feeding on 2-4 tons of prey every day.

There is a colonial organism that can be even larger than the blue whale.  That is the giant siphonophore, which may stretch over 100 feet. They're colonial organisms because they are made up of many bodies called zooids, which are specialized to perform different functions. Some are for movement, some for reproduction, some for eating, etc. All of these bodies are connected by a stem called a stolon, so they move together as if they were one organism.

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The Ocean Contains Many Undiscovered Species

Jellyfish (Tiburonia granrojo), a species described by MBARI and JAMSTEC researchers.
Jellyfish (Tiburonia granrojo), a species described by MBARI and JAMSTEC researchers. NOAA/Monterey Bay Aquarium Research Institute

While we can all probably name at least a few species that live in the ocean, there are many that have not even been discovered.  Only a small percentage of the ocean has been explored in any detail. In an effort to  address this, over 2,000 researchers participated in the Census of Marine Life, which occurred from 2000-2010. This was a bold effort to study new areas and find new species that resulted in many exciting discoveries, including more than 6,000 potentially new species. 

Lasting products from the Census include the Ocean Biogeographic Information System (OBIS) database, maps of the breeding and migration areas of marine species, and information on historic and current impacts on the marine environment.  The Census also laid the foundation for many current studies and collaborations. 

In 2012, a study by Appeltans, et.al, sought to find out how many species were in the ocean, and how many were yet to be discovered. They found that scientists have cataloged about 226,000 species. There are 58,000-72,000 species that have been collected and are in museums or other facilities but haven't been described (thus, they are potentially new species).  Based on computer modeling, they estimated that there are 700,000 to 1 million species in the ocean. 

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The Ocean is Home to Many Endangered Species

Diver observes Goliath grouper (Epinephelus itajara), a critically endangered species, in Molasses Reef, Key Largo, FL
Diver observes Goliath grouper (Epinephelus itajara), Key Largo, FL. Fotosearch / Getty Images

Although we've discovered some of the ocean, we haven't always done a good job respecting the habitat and the species that live there. From historic whaling and overfishing and current problems like illegal fishing, bycatch, marine pollution, warming ocean temperatures and ocean acidification, the ocean faces many threats.

The IUCN Red List contains over 70 critically endangered species, just in marine habitats. Species include the hawksbill turtle, goliath grouper, black abalone, vaquita, totoaba (whose harvest is causing the vaquita's extinction), smalltooth sawfish, Atlantic sturgeon, and many other species.

Although sometimes problems facing the ocean seem overwhelming, there are solutions. There are many easy things you can do, even at home, to help endangered marine life. These include using less energy, using reusable items instead of disposable ones, eating sustainable seafood, picking up litter and supporting ocean conservation and research organizations. 

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