World's Sixth-Largest River Discovered Under the Black Sea

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.

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