25 Things You Didn't Know About the World's Oceans

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In 2008, the United Nations recognized World Oceans Day on June 8 as a time to celebrate the immense bodies of water that make up roughly 70 percent of the surface of the Earth. The goal of the day is to promote conservation efforts and engage activists in preserving these five crucial areas—the Pacific, Atlantic, Indian, Arctic, and Southern (Antarctic) Oceans—and their inhabitants.

If you don’t know much about the deep blue sea—like why it's not actually blue, for example—check out 25 facts we’ve culled about the world’s largest and most fascinating real estate.

1. THE SUN GIVES IT THAT BLUE TINT.

A look at calm, blue ocean waters
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One of the most indelible features of the oceans is the deep blue waters that are continually churning, rolling, and coming in waves. The color is the result of the sun’s red and orange wavelengths being absorbed by the surface and its blue wavelengths penetrating deeper, giving way to a blue tint. And because those wavelengths can travel further down, the ocean will tend to appear more blue the lower you go. Why isn't water in a glass blue when you're sitting outdoors? There aren't enough molecules to absorb the light.

2. THEY'RE KEEPING THE INTERNET ONLINE.

If you could catch sight of the miles of cable criss-crossing the world’s oceans, it would look like a giant, submerged web. Communications companies maintain international connections by feeding cables down to (hopefully) flat surfaces on the ocean floor. Some require shark-proof layers to prevent predators from biting into your Netflix stream (although the danger of sharks has been vastly overhyped—human activity is a far bigger threat).

3. THE DEEPEST PART IS REALLY, REALLY DEEP.

The Mariana Trench is considered to be the deepest part of the world’s oceans. Inside of the Trench is a valley known as Challenger Deep that extends roughly seven miles (36,070 feet) below the surface. For comparison, the entirety of Mount Everest—at 29,029 feet—could easily be accommodated there. Manned explorations haven’t gone any further than 35,797 feet below the surface, a record set by two oceanographers in 1960. In 2012, filmmaker James Cameron explored roughly the same depths in a solo mission. It’s considered the deepest point on Earth.

4. SOUNDS CAN TRAVEL TO THE DEEPEST EXPLORED AREAS.

Researchers once lowered an underwater microphone called a hydrophone to almost the bottom of the Mariana Trench to see what sounds—if any—it might pick up. After feeling relieved the immense pressure at those depths—about 8 tons per square inch—didn’t implode the equipment, they discovered that sound from earthquakes, passing baleen whales, and other ambient noise was audible.

5. LAKES AND RIVERS LIE BENEATH THE SURFACE.

Some surfaces in the ocean feature sights that don’t seem to make any logical sense—rivers and lakes, some of them miles long, can stretch across the ground even though they’re submerged. How can a body of water exist in a body of water? Water from under the sea floor seeps up and dissolves salt layers, forming depressions. Because the water in the depression is more dense than the water all around it, it settles into the depression and forms a distinct pool.

6. THERE ARE 20 MILLION TONS OF UNTOUCHABLE GOLD IN THE OCEANS.

If you’re hoping to find a fortune in gold prospecting, don’t expect the ocean to cooperate. You may be able to plunder a shipwreck, but you won’t be able to collect much of the 20 million tons of gold estimated to exist in the water. That’s because it’s so diluted that it’s measured in parts per trillion. One liter of seawater might net you a 13-billionth of a gram.

7. WE KNOW MORE THAN YOU MIGHT EXPECT.

A dolphin swims in the ocean
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You might see mentions that we’ve "mapped" more of Mars than we have the Earth’s oceans, but that’s not quite true. Oceanographers have been able to visualize almost 100 percent of the ocean floors, albeit in a resolution that makes it difficult to spot a lot of detail. In that sense, images of Mars and other planets have been able to offer more information because they’re not covered in water that can block radar. Although we haven't explored the vast majority of the oceans first-hand, technology has enabled us to have a rough idea of their layouts.

8. THE BIGGEST WATERFALL ON EARTH IS IN THE ATLANTIC.

Putting Niagara Falls to shame is the Denmark Strait, a waterfall below the Atlantic Ocean that, in terms of water volume, is the equivalent of 2000 of the world’s most notable waterfalls, with cascading liquid pouring 11,500 feet down. The Strait’s cold water on the eastern side is more dense than the warm fluid coming from the west. When the two waters mix, the colder supply sinks, creating a waterfall.

9. WE DON'T KNOW ANYTHING ABOUT MOST OF THE MARINE LIFE.

An octopus is photographed by an ocean photographer
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Size and water pressure conspire to limit our exploration of the oceans, so much so that it’s estimated we’ve identified only one-third of the potential marine life lurking beneath the surface. It’s possible most of those are smaller organisms, but it’s likely that some whales and other mammal species have yet to be discovered. We’re making progress, though: An average of 2000 new species are described each year.

10. MAGELLAN NAMED THE PACIFIC OCEAN.

When Ferdinand Magellan crossed the Atlantic beginning in 1519, he eventually found his way to another body of water—what he dubbed the Pacific, or peaceful, ocean due to the calm surface. He didn’t know it at the time, but the Pacific would eventually be recognized as the largest ocean on the planet at 59 million square miles.

11. THE MOST REMOTE PLACE ON EARTH IS IN THE SOUTH PACIFIC.

Point Nomo is illustrated
Courtesy National Oceanic and Atmospheric Administration

Known as Point Nemo, the area is roughly 1000 equidistant miles away from the coasts of three neighboring islands and so remote that astronauts are often closer to any theoretical occupants than anyone on dry land.

12. MOST VOLCANIC ERUPTIONS ARE UNDERWATER.

Up to 80 percent of volcanic eruptions go unnoticed by land-dwellers. That’s because they’re erupting underwater. An estimated one million volcanoes—some extinct and some very active—spew molten hot lava. Despite the heat, creatures can still be found near their superheated vents. Researchers believe these areas harbor several undiscovered species that are invulnerable to the harsh conditions, including water temperatures up to 750 degrees Fahrenheit.

13. THERE MAY BE BILLIONS IN SUNKEN TREASURE DOWN IN THE DEEP.

A sunken ship sits on the ocean floor
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It’s impossible to offer an accurate estimate of how many shipwrecks and accompanying treasures are lurking in the oceans, but a few people have made an honest effort of it. The National Oceanic and Atmospheric Administration (NOAA) thinks a million sunken ships lurk in the dark; others peg the total value of the unrecovered treasures at $60 billion. So why don’t we hear more stories of watery grave-robbing? Because governments or private parties are likely to make a legal claim to those funds, making an expensive expedition for treasure a gamble at best.

14. THEY KEEP US BREATHING.

Forget all the beauty and wonder of the world’s oceans: At the bare minimum, they’re responsible for supplying us with oxygen. Oceans produce 70 percent of the oxygen supply in the atmosphere thanks to marine plants releasing it as a byproduct of photosynthesis. One phytoplankton, Prochlorococcus, is estimated to be solely responsible for one in every five breaths a human will take.

15. "DEAD ZONES" CAN BE BARREN OF ANY LIFE.

Dark ocean waters can be devoid of life
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One reason pollution is such an issue for oceans: It can rob them of the oxygen needed to support life. When run-off from waste disposal gets into the water, it can feed an overabundance of algae, which then dies, sinks, and as it decomposes, consumes the available oxygen in the water. That creates hypoxic areas, or hot spots with a lack of oxygen. If fish and other marine life don’t find a new space to dwell in, they’re toast.

16. THE FISH ARE EATING A LOT OF PLASTIC.

With over seven million tons of plastic winding up in the ocean each year, it’s inevitable that a lot of it winds up as part of an unwelcome addition to a fish’s diet. For fish in the northern Pacific, researchers at the University of California, San Diego once estimated they swallow between 12,000 and 24,000 tons every year.

17. KEEPING TROPICAL PET FISH MIGHT BE HARMING THE OCEANS.

Colorful tropical fish swim in the water
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Those aquariums in pet stores and dental offices might remind you of marine life, but they might also be having a negative impact. When tropical fish are caught, fishermen use sodium cyanide to make them float out of the reef for easy scooping. While the hope is that it just stuns them, the residue of the chemical can bleach coral reefs and kill scores of other fish.

18. TSUNAMI WAVES CAN REACH 100 FEET...

When waves reach shallow water near land, energy that would normally be dispersed goes up, elongating the wave. A 1958 earthquake and landslide in Alaska generated a tsunami 100 feet high and destroyed all vegetation up to 1720 feet, the largest in recorded history.

19. ...BUT THE BIGGEST WAVES ARE UNDER THE SURFACE.

Called internal waves, these water walls have been found three miles below the surface. The waves are part of water layers with different densities and can reach heights of 800 feet before collapsing. Scientists believe these massive forces can help move heat and nutrients to other areas.

20. WE'RE TRYING TO MAKE THE OCEAN DRINKABLE.

As most everyone knows, drinking salt water is perilous at best and deadly at worst. In a process called desalination, that salt is removed, leaving fresh water. But building facilities and the energy required to process water this way has traditionally been more expensive than sourcing water from potable sources.

21. THE BRISTLEMOUTH IS THE MOST ABUNDANT VERTEBRATE IN THE WORLD.

A bristlemouth snacks on a shrimp
Courtesy National Oceanic and Atmospheric Administration

Not familiar? If you saw one, you’d know. The bristlemouth is a fish a little smaller than your average human finger that has a mouth full of fangs and can glow in the dark. It’s also the most common vertebrate in the world. For comparison? Chickens could number as many as 24 billion on land, while bristlemouths are said to add up to the hundreds of trillions.

22. GIANT KELP GROWS VERY QUICKLY.

Giant kelp, or Macrocystis Pyrifera, is a type of seaweed that experiences an astonishing growth spurt. To reach its usual height of 100 feet, the species can grow up to two feet in a single day.

23. RUBBER DUCKS HAVE HELPED OUR UNDERSTANDING OF THE OCEANS.

A rubber duck floats in the water
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In 1992, a shipment of bath toys was headed from China to the U.S. when the cargo ship dropped a container. More than 28,000 rubber ducks—or duckies, depending on your preference—and other play-animals were dumped into the North Pacific Ocean. Oceanographers tracked where the ducks wound up in order to better understand the water currents, with some landing ashore in Europe and Hawaii. The duck sightings didn’t ease up until the mid-2000s.

24. ANTARCTIC FISH HAVE NATURAL ANTIFREEZE.

Curious how aquatic life can survive the temperatures at the poles? Antifreeze proteins in the fish prevent ice crystals from growing, preventing their blood from being overcome by the chill and allowing it to continue flowing.

25. SEASHELLS DON'T ACTUALLY SOUND LIKE THE OCEAN.

A child holds a seashell up to her ear
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Seashells have long been perceived as the iPods of the sea, tiny little devices that can mimic the static, hissing noise of the water. What they’re actually doing is acting as a resonator, or a cavity that allows sound to vibrate. By holding up the shell to your ear, you’re hearing the ambient noise around you amplified. All that whooshing air typically sounds a lot like the movement of cascading waves. If you can't make it to beach, though, it might be the next best thing.

More Than 350 Franklin Expedition Artifacts Retrieved from Shipwreck of HMS Erebus

Drone image above the HMS Erebus shipwreck.
Drone image above the HMS Erebus shipwreck.
Parks Canada's Underwater Archaeology Team

From a shallow Arctic gulf, a treasure trove of objects from the HMS Erebus shipwreck has been brought to the surface for the first time in more than 170 years. The items could offer new clues about the doomed Franklin expedition, which left England in 1845 to search for the Northwest Passage. All 129 people perished from still-uncertain causes—a mystery that was fictionalized in the AMC series The Terror in 2018.

Marc-André Bernier, head of underwater archaeology at Parks Canada, said in a teleconference from Ottawa that this year’s research season was the most successful since the discovery of the HMS Erebus shipwreck in 2014. Parks Canada divers and Inuit located the HMS Terror, the second ship of the Franklin expedition, in 2016.

Parks Canada diver at HMS Erebus shipwreck
A Parks Canada diver retrieves a glass decanter at the HMS Erebus shipwreck.
Parks Canada's Underwater Archaeology Team

From mid-August to mid-September, 2019, the Parks Canada and Inuit research team began systematically excavating the large and complex shipwreck. “We focused on areas that had not been disturbed since the ship had sunk,” Bernier said. “Right now, our focus is the cabins of the officers, and we’re working our way toward the higher officers. That’s where we think we have a better chance of finding more clues to what happened to the expedition, which is one of the major objectives.”

Over a total of 93 dives this year, archaeologists concentrated on three crew members’ cabins on the port side amidships: one belonging to the third lieutenant, one for the steward, and one likely for the ice master. In drawers underneath the third lieutenant’s bed, they discovered a tin box with a pair of the officer’s epaulets in “pristine condition,” Bernier said. They may have belonged to James Walter Fairholme, one of the three lieutenants on the Erebus.

HMS Erebus shipwreck epaulets
A pair of epaulets, which may have belonged to third lieutenant James Walter Fairholme, was found at the HMS Erebus shipwreck.
Parks Canada's Underwater Archaeology Team

In the steward’s pantry, where items used to serve the captain were stored, divers carefully brushed away sediment to reveal dozens of plates, bowls, dish warmers, strainers, and more— about 50 serving pieces total. Bernier said some of the most exciting finds were personal objects that could be linked to individuals, such as a lead stamp with the inscription “Ed. Hoar,” for Edmund Hoar, the 23-year-old captain’s steward. They also found a piece of red sealing wax with a fingerprint of its last user.

Dishes at HMS Erebus shipwreck
Divers found dishes in the steward's pantry at the HMS Erebus shipwreck.
Parks Canada's Underwater Archaeology Team

Other intriguing items brought to the surface include a glass decanter, found in the officers’ mess area on the lower deck, which may have held brandy or port; a high-quality hairbrush with a few human hairs still in the bristles; and a cedar-wood pencil case. All of the artifacts are jointly owned by the Government of Canada and Inuit.

Hairbrush from HMS Erebus shipwreck
A hairbrush discovered at the HMS Erebus shipwreck still had a few human hairs in the bristles.
Parks Canada's Underwater Archaeology Team

The extensive recovery was made possible by a new research barge, which was moored over the shipwreck and provided hyperbaric chambers and hot-water suits. While wearing the suits, divers were able to stay in the frigid waters for about 90 minutes at a time; they spent over 100 hours examining the wreck this year.

The HMS Erebus’s size and excellent state of preservation mean there’s much more to discover, Bernier said. The Erebus is 108 feet long, and though the upper deck has collapsed, there are 20 cabins on the main deck. They’ve examined only three so far. “There are tens of thousands of artifacts still there,” Bernier tells Mental Floss. “We’re going to be very focused and save what needs to be saved, and go to places [in the wreck] where there are good chances of finding the most information that is valuable for the site.”

Parks Canada and Inuit archaeologists
Parks Canada and Inuit archaeologists set up instruments near the HMS Erebus shipwreck.
Parks Canada's Underwater Archaeology Team

As with the findings from previous research seasons, many questions about the shocking demise of the Franklin expedition remain unanswered. How and when did the HMS Erebus sink after both ships were abandoned in spring 1848, having been trapped in ice since September 1846? Which officers and crew were among the 24 men who had died by that time, and why so many?

Bernier tells Mental Floss there’s even a new mystery to solve. Near Edmund Hoar’s items, divers found another artifact that also bore the name of a crew member—mate Frederick Hornby. “Originally, when the ships set sail, he was not on Erebus, he was on Terror,” Bernier says. “So this object jumped ship at one point. How did that happen? Was Hornby transferred to Erebus; did they abandon one ship and put everybody on the other one? Was it something somebody recovered after he died? Was it given to somebody? With one object, we can start to see [new] questions. Hopefully, by piecing all of this together, we can actually start pushing the narrative of the story in some interesting direction.”

The Reason Our Teeth Are So Sensitive to Pain

This woman's tooth pain is actually helping her avoid further damage.
This woman's tooth pain is actually helping her avoid further damage.
champja/iStock via Getty Images

On a good day, your teeth can chew through tough steak and split hard candy into pieces without you feeling a thing. But sometimes, something as simple as slurping a frosty milkshake can send a shock through your tooth that feels even more painful than stubbing your toe.

According to Live Science, that sensitivity is a defense mechanism we’ve developed to protect damaged teeth from further injury.

“If you eat something too hot or chew something too cold, or if the tooth is worn down enough where the underlying tissue underneath is exposed, all of those things cause pain,” Julius Manz, American Dental Association spokesperson and director of the San Juan College dental hygiene program, told Live Science. “And then the pain causes the person not to use that tooth to try to protect it a little bit more.”

Teeth are made of three layers: enamel on the outside, pulp on the inside, and dentin between the two. Pulp, which contains blood vessels and nerves, is the layer that actually feels pain—but that doesn’t mean the other two layers aren’t involved. When your enamel (which isn’t alive and can’t feel anything at all) is worn down, it exposes the dentin, a tissue that will then allow especially hot or cold substances to stimulate the nerves in the pulp. Pulp can’t sense temperature, so it interprets just about every stimulus as pain.

If you do have a toothache, however, pulp might not be the (only) culprit. The periodontal ligament, which connects teeth to the jawbone, can also feel pain. As Manz explains, that sore feeling people sometimes get because of an orthodontic treatment like braces is usually coming from the periodontal ligament rather than the pulp.

To help you avoid tooth pain in the first place, here are seven tips for healthier teeth.

[h/t Live Science]

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