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Underwater & Undersea Rivers (Distinct Submerged Streams Or Bodies Of Water)

This thread is being established to house a vintage post tangential to its original location and to provide a space for posts on similar natural phenomena.
 
Spudrick68's original link is still 'good'. Here's the introductory text from the linked page, to give an idea what it's about ...

... In Mexico's Yucatan Peninsula, visit Cenote Angelita (“Little Angel”) and then get ready to experience a dive unlike any other. Just a ten to fifteen minute drive south of Tulum will lead you to Cenote Angelita—an advanced scuba diving cenote (water-filled cave) that houses a surreal surprise: an underwater river that flows through the ocean!

How is this possible? you might be wondering. Well, when limestone bedrock collapses, it sinks and forms a pit. Acting as a reservoir, this pit then fills with a mixture of fresh groundwater and saltwater. Eventually, organic matter ends up in the trench, and when it decomposes, it produces a halocline (a cloud of hydrogen sulphide) that separates the freshwater at the top from the saltwater below.

Divers can actually swim right through this cloud, which magically resembles a flowing body of water. With fallen leaves and branches lining the “river,” you can't help but think you're in a mystical forest.
 
Another version of an underwater river is a distinct course of cold water flowing underneath the sea. Here's an example from 2011 ...

Underwater 'Rivers' Discovered on Ocean Floor
An underwater "river" has been discovered snaking along the ocean bed off southwestern Australia.

The undersea phenomenon — layers of dense water that creep along the ocean floor at a rate of about a half-mile (1 km) a day — was found to be some 65 feet (20 meters) thick and stretches for more than 60 miles (100 kilometers).

Researchers say it's the first time these rivers have been glimpsed in such warm waters.

"These dense shelf water cascades are common in high-latitude regions as a result of ice formation, but this is the first time these processes have been discovered in sub-tropical regions, and to be present throughout the year," said the University of Western Australia's Chari Pattiaratchi in a statement.

Water evaporation during the region's summers, followed by cooling during the winters, fuels the formation of the rivers, Pattiaratchi said, leading to the gathering of high-density waters in the coastal shallows, which then flow offshore as slow-moving rivers.

So-called underwater rivers have been discovered in different spots around the globe. ...

The Australian underwater river was uncovered by seafaring gliders, self-propelling robots equipped with sensors to detect water temperature, salinity, plankton productivity, turbidity and dissolved oxygen. They can operate nonstop in the water for up to eight months. ...

SOURCE: https://www.livescience.com/14516-underwater-rivers-discovered.html
 
There's a large underwater river in the Black Sea ...

Black Sea undersea river
Illustration of the Black Sea, from NASA’s World Wind globe software. The Bosphorus Strait can be seen at lower left.
The Black Sea undersea river is a current of particularly saline water flowing through the Bosphorus Straitand along the seabed of the Black Sea. The discovery of the river, announced on 1 August 2010, was made by scientists at the University of Leeds, and is the first of its kind in the world.[1] The undersea river stems from salty water spilling through the Bosphorus Strait from the Mediterranean Sea into the Black Sea, where the water has a lower salt content. ...

FULL ARTICLE: https://en.wikipedia.org/wiki/Black_Sea_undersea_river

Remarkable Rivers With Trees, Leaves And Waterfalls Hidden Under The Sea!
Rivers under the sea can really exist! The ocean has many secrets, and underwater rivers are among them.

There is a massive underwater river flowing along the bottom of the Black Sea. This amazing undersea river is complete with trees and leaves flowing on the sea bed, and even waterfalls!

It is estimated that if on land, the undersea river would be the world’s sixth largest in terms of the volume of water flowing through it. It is about 350 times greater than the River Thames and 10 times greater than Europe’s biggest river, the Rhine. ...

FULLL STORY: http://www.messagetoeagle.com/remar...s-leaves-and-waterfalls-hidden-under-the-sea/
 
Underwater 'Rivers' Discovered on Ocean Floor
SOURCE: https://www.livescience.com/14516-underwater-rivers-discovered.html

Subsequent research into these Australian sub-sea rivers has found them to be influential and somewhat seasonal ...

The researchers found that the underwater rivers are a regular occurrence during the fall and winter months in Australia across a span of 6,213 miles (10,000 kilometers). In the new study, the researchers also found that the underwater rivers could withstand high winds and high tides that often stir up the water, a finding that's a "unique occurrence globally," the authors wrote in the study.

The underwater gliders were also equipped with sensors to detect organic matter and chlorophyll, a green pigment found in plants, algae and cyanobacteria. The underwater rivers in Australia, they found, serve as transport channels for material and matter across the continental shelf and deeper into the ocean. "The coastal ocean is the receiving basin for suspended and dissolved matter that includes nutrients, plant and animal matter and pollutants. and represents an important component of the ocean environment, connecting the land to the deeper ocean," senior author Yasha Hetzel, a researcher at The University of Western Australia's Oceans Graduate School, said in the statement.

Massive underwater rivers were discovered off the coast of Australia
https://www.livescience.com/underwater-rivers-discovered-australia.html

PUBLISHED RESEARCH REPORT:
https://www.nature.com/articles/s41598-020-66711-5

See Also:
https://www.sciencealert.com/a-myst...vers-appears-to-surround-the-australian-coast
 
Underwater Avalanche Severs Telecom Cables

slowing the internet and other data traffic between Nigeria and South Africa

The 'avalanche' descended into the Congo Canyon, one of the few such submarine features directly connected to a major river mouth
Scientists are reporting what they say is the longest sediment avalanche yet measured in action.

It occurred underwater off West Africa, in a deep canyon leading away from the mouth of the Congo River.

Something in excess of a cubic kilometre of sand and mud descended into the deep.

This colossal flow kept moving for two whole days and ran out for more than 1,100km across the floor of the Atlantic Ocean.

The underwater avalanche - more properly called a turbidity current - was initiated on 14 January last year. It's only being reported now because scientists needed time to recover the sensors and fully analyse their data.

The team says two factors combined to prime and then trigger the prodigious flow.

The first was an exceptionally large flood along the Congo River in late December 2019. A 1-in-50-year occurrence, this delivered vast quantities of sand and mud to the head of the underwater canyon. But this was still two weeks before the slide.

What followed in January, however, were some unusually big spring tides.
"The turbidity current we think was triggered at low water, at low tide," said Prof Dan Parsons from Hull University.

"As the loading of the ocean above declines, so you get a change in the pore water pressure within the sediment - and that's what allows it to fail.

"But first you have to load the dice by delivering the sediment. Then the tidal signature can kick everything off."
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