Black Sea undersea river

[1] The river system formed roughly 7,500 years ago when the Bosphorus developed its two-way depth-separated flow.

The team used the Natural Environment Research Council's Autosub3 – a 7-metre torpedo-shaped autonomous underwater vehicle – to get as close to the current as possible.

Though smaller than the Amazon channel, the undersea river still carried ten times more water than the Rhine.

One major difference is that the underwater river, when rounding a bend, moves in currents spinning in the opposite direction from those on land.

[1] The river works as a density current, because it carries sediments along the sea floor and has a higher salinity than the surrounding water.