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It’s difficult to overstate how vast the world’s ocean is. It covers approximately 70% of Earth’s surface and accounts for a staggering 97% of all water on the planet. Scientists estimate that up to 95% of the world’s ocean has yet to be explored. Technically, Earth has one giant ocean, which is geographically divided into the Pacific, Atlantic, Indian, Southern (also known as Antarctic), and Arctic Oceans. Connected to these bodies of water are dozens of smaller seas such as the Arabian Sea, Mediterranean Sea, and Red Sea. Within their waters, you’ll find incredible diversity of marine life, some of the planet’s most impressive geological formations, millions of sunken treasures, and countless other surprises. Discover more about the water that flows around us by diving into these 20 fascinating facts about the world’s oceans.
Oceans Are a Huge Source of Oxygen
According to the National Ocean Service, scientists estimate that the ocean produces between 50% to 80% of Earth’s oxygen — thanks to marine plankton such as algae, bacteria, and drifting plants. These minuscule beings, which are invisible to the naked eye, absorb carbon dioxide and then produce oxygen through photosynthesis. The Prochlorococcus is one of the most abundant photosynthetic organisms and is responsible for approximately 20% of our biosphere’s oxygen.
The Sun Gives the Oceans Their Blue Color
Contrary to popular belief, the blue color of an ocean doesn’t occur because the blue sky is reflected in the water. It’s actually produced by the way that water absorbs sunlight. When the sun’s rays hit an ocean, it absorbs red and orange-hued long-wavelength light, plus violet and ultraviolet short-wavelength light. What remains are the blue wavelengths, hence the expressions “deep blue sea” and “blue planet.” However, the blue color only occurs with large amounts of water. For example, a glass of tap water appears transparent because it doesn’t have enough molecules to absorb the light.
Coral Can Produce Its Own Sunscreen
Humans aren’t the only ones who have to protect themselves against UV radiation caused by sunlight. Overexposure can severely damage the skin of coral and the algae that lives inside them, particularly in shallow waters. Fortunately, coral can produce nature’s version of sunscreen to regulate its exposure to the sun. This is achieved by the creation of fluorescent pigments from special proteins found inside the coral tissue. Scientists are studying if it can be extracted and used in the production of sunscreen for humans.
Southern Ocean Fish Have a Natural Antifreeze
The waters around Antarctica are cold, with temperatures ranging from just 28 to 50 degrees Fahrenheit. The only reason they don’t freeze is because of the salt present in the water. Despite the harsh conditions, the Southern Ocean (also known as the Antarctic Ocean) is teeming with marine life. The notothenioid fish is an abundant species that can withstand the chilly waters around Antarctica thanks to a biological trait called glycoprotein. This acts as a natural antifreeze by preventing ice crystals from forming in the blood. As a consequence, notothenioids make up about 90% of Antarctica’s fish biomass.
Earth's Longest Mountain Range Is Underwater
Stretching for 4,300 miles through Central and South America, the Andes mountain range is Earth’s longest — above ground. But the Andes don’t hold a candle to the almost-entirely underwater Mid-Ocean Ridge. Crisscrossing the planet like the stitches on a baseball, this underwater range covers an incredible 40,389 miles. It’s formed by the movement of tectonic plates and consists of mountains and valleys. Many of the world’s volcanoes also rise up from the range’s boundaries.
The World’s Highest Mountain Is Also (Partly) Underwater
Ask anyone what the world’s tallest mountain is, and chances are they’ll say Mount Everest. Everest does have the highest elevation above mean sea level. However, if you measure from base to peak, Hawaii’s Mauna Kea eclipses Everest by almost a mile. Starting from its origin at the base of the Pacific Ocean, Mauna Kea has a total height of 33,500 feet. Above ground, the dormant volcano is a trekker’s paradise, and those who reach the summit can claim to have climbed the world’s tallest mountain, even though almost two-thirds of it lies below the water's surface.
The World’s Tallest Waterfall Is Underwater, Too
On land, the tallest visible waterfall is Venezuela’s 3,211-foot-high Angel Falls. It’s an impressive height, yet it pales in comparison to the 11,500-foot-tall Denmark Strait Cataract. This underwater waterfall is found on the Arctic Circle, between Iceland and Greenland. Here, southward-flowing cold water from the Nordic Sea meets the warmer waters of the Irminger Sea. The cold water is denser, so it sinks and spills over a drop in the ocean floor. The waterfall’s flow rate is 50,000 times greater than that of Niagara Falls.
An Iceberg Can Supply Drinking Water to One Million People
Icebergs are pieces of freshwater that break free from glaciers and ice shelves and then float around the frigid Antarctic and Arctic oceans. An average-sized iceberg contains approximately 20 billion gallons of water. That’s enough to supply drinking water to one million people — for over five years. That said, it’s not particularly easy to tow an iceberg to water-starved countries without it melting prior to arrival. However, the United Arab Emirates Iceberg Project is attempting to do just that by transporting icebergs 7,500 miles from the South Pole to the coast of Fujairah.
The Mariana Trench Is Home to Earth’s Deepest Point
About 330 miles north of Guam is a crescent-shaped dent in the Pacific Ocean floor called the Mariana Trench. Its deepest point is known as Challenger Deep, which sits at 6.8 miles below sea level, making it the deepest place on Earth. As you’d imagine, the trench is incredibly dark and cold, but it is home to a surprising amount of sea life — including some of the world’s strangest creatures that can survive such conditions. The water pressure in the trench is equivalent to the weight of 48 jumbo jets piled on top of a human body. To date, only three divers have explored Challenger Deep. Film director James Cameron was the first to do so on a solo expedition, when he recorded footage for a documentary called Deepsea Challenge 3D.
Almost All Life on Earth Is Aquatic
Since the ocean covers more than 70% of the Earth’s surface, it probably comes as no surprise that it’s swarming with colorful creatures. But perhaps more surprising is that researchers estimate that 94% of all life on Earth is aquatic. That makes those of us that reside on land part of an extremely small minority. The World Register of Marine Species currently recognizes 236,340 marine species. However, with as much as 95% of oceans still unexplored, about two-thirds of aquatic species are yet to be identified.
The World’s Largest and Smallest Animals Are Ocean Dwellers
You don’t need to be a big fish in a small pond to be significant. Ranging from 40 to 400 nanometers, marine viruses are the definition of microscopic. To put that into perspective, a nanometer is one-billionth of a meter. As tiny as they are, marine viruses are among the most abundant life-forms and can be destructive to other marine life. At the other end of the scale, the blue whale grows to an average length of 95 feet, about the length of a basketball court.
Earth’s Largest Living Structure Is in the South Pacific
Australia’s Great Barrier Reef is the world’s largest living structure, covering about 133,000 square miles. That’s greater than the United Kingdom, the Netherlands, and Switzerland combined. Astronauts can even see it from outer space. The reef stretches approximately 1,500 miles along the coast of Queensland, in east Australia, and shelters billions of living species. This includes the world’s largest collection of coral reefs, over 1,500 fish species, six species of sea turtles, and 17 varieties of sea snakes.
The Pacific Ocean Is Wider than the Moon
The world’s largest ocean, the Pacific has a surface area of 60 million square miles. It’s about 50% bigger than the Atlantic, which is the second largest ocean on the planet. At its widest point, the Pacific stretches for 12,300 miles from Indonesia to Colombia. This doesn’t just make it wider than the moon’s diameter (2,160 miles) — it makes it more than five times wider. Scientists estimate that it would take a person 91 days to walk around the moon. Therefore, it would take almost 580 days to cross between the eastern and westernmost points of the Pacific — that is, if the person could walk on water.
One Location in the Ocean Is Closer to Space than Land
Deep in the South Pacific Ocean there’s a place called the oceanic pole of inaccessibility, the place in the ocean that lies at the greatest distance from land. Known as Point Nemo — a reference to the protagonist of Jules Verne’s 20,000 Leagues Under the Sea — the location is about 1,670 miles from the nearest points on land: Ducie Island (Pitcairn Islands), Motu Nui (Easter Islands), and Maher Island (Antarctica). Since the International Space Station flies roughly 250 miles above Earth, this faraway location is technically closer to outer space than anywhere on land.
The Mediterranean Sea Used to Be a Dry Basin
Connected to the Atlantic Ocean, the Mediterranean Sea stretches from the Strait of Gibraltar to the western shores of the Levant region. The Mediterranean Basin was a cradle of ancient civilizations such as the Greeks and Phoenicians, yet six million years ago, tectonic plate movement isolated the basin from the Atlantic. It was a desertlike region peppered with salt-water pools, until the Zanclean Flood refilled the basin through the Strait of Gibraltar at speeds of up to 100 miles per hour. The flood created a dramatic coastline that’s dotted with hundreds of beloved tourist destinations today.
Oceans Are a Rich Source of Gold
It’s estimated that the world’s oceans are home to about 20 million tons of gold. That’s the equivalent of $771 trillion, but don’t expect to find gold ingots washed up on a beach somewhere. The gold in question is made up of extraordinarily small fragments — 13 billionths of a gram in every liter of seawater. Sifting the ocean’s gold is near impossible, and there’s no cost-effective way to mine it. So for now, the oceans maintain their unfathomable and untouchable wealth.
The Pacific Ocean Is Home to 25,000 Islands
Sheltering around 25,000 islands, the Pacific Ocean has more islands than anywhere else on Earth. They range from New Guinea, the world’s second-largest non-continental island, to Nauru, the planet’s smallest independent island nation. The Pacific is also home to the Galapagos Islands, the archipelago that inspired Charles Darwin to formulate his theory of evolution.
Millions of Shipwrecks Lie in the World’s Oceans
UNESCO estimates that there are an astounding three million shipwrecks spread across the planet’s ocean floors. From the fleet of Mongol emperor Kublai Khan to the ships of Christopher Columbus and the RMS Titanic, shipwrecks are of immense historical value to archaeologists. They help us understand the lives of ancient civilizations, explorers, and merchants. They also attract myriad marine life, making them popular among marine biologists, scuba divers, and snorkelers. The Florida Keys National Marine Sanctuary alone is home to some 1,000 wrecks alone.
The Ocean Is One Big Museum
Thanks largely to those shipwrecks, the ocean is said to be home to more historical artifacts than all of the world’s museums combined. Scuba divers can plunge deep to discover sunken artwork and archaeological finds at fascinating underwater museums all around the planet. One estimate is that $60 billion worth of treasures lay embedded in the ocean floor. Indiana native Mel Fisher has made a living out of searching the seas for these treasures, and in 1985, he discovered the 17th-century Spanish galleon Nuestra Señora de Atocha off the coast of Florida. The recovered loot had a value of $450 million, including 40 tons of gold and silver.
Oceans Bring the Internet to Our Homes and Workplaces
In 1850, a transatlantic cable was laid on the ocean floor in order to send telegraphic messages between Ireland and Newfoundland, Canada. It sped up communication times between Europe and North America from 10 days to mere minutes. Today, 300 submarine communication cables stretch for a staggering 550,000 miles around the ocean floors. These cables are responsible for powering almost all international data and making the internet available worldwide. So while you're reading this, give special thanks to the oceans.