World's largest waterfall : underwater wild Denmark Strait

At 67º 46' N, the 280 km wide strait between Iceland and Greenland is an infamous ocean stretch of revolted wild waters and thick blizzards, a route every sailor prefers to avoid. Alistair Maclean wrote in one of his tales:

" (...) along the belt of the Arctic Circle itself, lie the most bitter seas in the world: and no part of it more bitter, more hostile to man and the puny ships that carry him across the savagery of its galetorn waters than that narrow stretch of ocean between Iceland and Greenland that men call the Denmark Strait.

From the far-ranging Vikings of a thousand years ago to the time of the modern Icelandic fishermen, ships have sailed through this narrow passage, but they sailed always at their peril, only when necessity dictated, and they never lingered long, never a moment more than they had to. No man, no ship, has ever waited there from choice, but, at rare intervals, some few men and ships have had to do it from necessity."

For once this strait was a historic site: during the 2nd World War, in 1941, there took place the legendary interception of the strongly armored battleship  Bismarck, the nazi super-weapon to blow up the naval supply convoys protected by older and less efficient British battleships. 

On that day, there was ice on the ocean to the North and a deep fog to south, but the sea was quiet enough.

The battle started unlucky for the British side: HMS Hood (above), a battlecruiser of almost 50 000 tons, was shattered and sunk by the first artillery shells, probably due to her flawed positioning facing the German ship. A disaster. Another Navy battleship, the Prince of Wales,  still fired some shells, failing most of them, and narrowly escaped with severe damages.

Bismarck in the blizzard, firing.

Well, it happens that after all some three of those shells did badly strike the Bismark, and the damage done caused fatal loss of speed and steering capability;  under Churchill's order "- sink the Bismarck !", the German warship, chased along a southernly route, was finally terminated by Navy torpedoes off the coast of Brittany. A shameful dishonor for the German pride, and about 4000 lives lost in this battle only.

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So, what about the waterfall? Denmark Strait  is a unique geological site. There are several waterfalls beneath the ocean surface, falling to the sea floor, and much higher than those on land; but this is the largest on the planet, whatever its kind - an unthinkable colossus, over 2 miles downfalling !

This waterfall is 160 km wide and falls almost 3505 m to the bottom of the ocean ! The flow rate is 3 to 5 million cubic meters per second, awesome.

Sailing out southwards through the Irminger Sea at 67º 46' can be as dreadful as the Drake Passage south of Cape Horn.

 

The Danes call it Grønlandspumpen, Greenland's Pump.

Now, the scientific explanation. A huge drop in the ocean floor and the warm surface current flowing northwards over the deep frigid current flowing southwards cause the slide of massive volumes of water downward along the slope, over 4000 times the volume of Victoria Falls.

As it occurs beneath the ocean's surface, the massive turbulence goes undetected for the common sailor.

Fed by warm northwards currents IC and NAC, two reverse cold overflowing currents, DSO e ISO, precipitate down the canyon southwest of Iceland.

NAC - North Atlantic Current
EGC - East Greenland Current
DSO - Denmark Strait Overflow
NIIC - North Icelandic Irminger Current
IC - Iceland Current
ISO - Iceland/Scotland ridge Overflow

Nearest settlements: Isafiordur and Sudavik (Iceland), Ittoqortoormiit (Greenland).