This color-augmented 3-D radar image shows where the undersea channel enters the Black Sea from the Bosphorus. Photo by University of Leeds via the Daily Mail
The broad and powerful Bosphorus defines Istanbul, splitting the city into two continents and solidifying its importance over centuries as a transit and trading route. Anyone who's been out on its waters knows the strength of the strait and has likely noticed the two treacherous currents flowing in opposite directions, one of which, it has recently been discovered, is strong enough to have carved out a massive undersea river -- believed to be the only one of its kind still flowing.The undersea river, up to 115 feet deep in places, carries a volume of water 10 times greater than Europe's biggest river, the Rhine, along the sea bed, "carving out channels much like a river on the land," the Telegraph reported earlier this month, noting that the river even has rapids and waterfalls.
"If found on land, scientists estimate it would be the world's sixth largest river in terms of the amount of water flowing through it," the paper wrote.
Surveyed with a Robotic Submarine
Scientists from the University of Leeds were the first to survey the channel, using a robotic submarine. They found that the dense, salty water from the Marmara Sea -- which leads out to the Aegean and Mediterranean Seas at the other end of the Bosphorus -- is flowing out of the strait and along the bottom of the Black Sea, carrying along sediment and nutrients that could be key in providing vital nutrients to remote parts of the ocean.
"Scientists have long suspected [undersea rivers] can form, after sonar scans of the sea bed have revealed meandering channels in many of the world's oceans, although none have been found before to have currents of water flowing through them," the Telegraph wrote.
"Most are believed to have formed when sea levels were much lower and the channels have been found to be up to 2,500 miles long and be several miles wide. The channel in the Black Sea, although much smaller, is the only one to be found still flowing and proves that these mysterious channels are formed by underwater rivers."
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