Whirlpools are like giant squid: one feels that they are almost mythical. They have been the subject of stories, legends and poems, and yet they are real and – if you’re lucky – can be seen and visited.
Simon Winchester, author of Atlantic, writes beautifully of a visit to the Corryvreckan whirlpool between the islands of Jura and Scarba, two of the inner Hebridean Islands off Scotland. I’ve read accounts of diving this incredible (and terrifying) water feature in Rod MacDonald’s books, The Darkness Below and Into the Abyss. His interest in this whirlpool was piqued after seeing it marked on a map, and wondering whether it was really a whirlpool, or whether it would be a disillusioning sign that British map making was not all he believed it to be.
He follows this visit with trips to see other whirlpools, and some research into their provenance. The word maelstrom, meaning a large vortex of water, is derived from the name of a whirlpool called Moskstraumen, in the Lofoten archipelago of Norway. This particular system of eddies featured in an Edgar Allan Poe story (A Descent into the Maelstrom).
Whirlpools are the result of winds, tides and currents interacting with underwater topography, generated when great volumes of water are forced over suddenly shallow outcrops of rock. Winchester says:
In other words, whirlpools—the Maelstrom especially, the others most probably—are fluid marine phenomena that have solid submarine causes. There is the pinnacle that rises underneath the Saltstraumen. There is a shelf of rock that rears up in the Corryvreckan. There are shallows that the charts of Norway show south of Lofoten Point. There are ridges of rock under Japan’s Naruto Strait such as to allow a bridge to be built across it. And a number of near-islands loom perilously beneath the keels of such boats as pass beside the international boundary in the tidal estuary that divides the state of Maine from the Canadian province of New Brunswick.
Shallowing, in short, is what it is all about. A narrow passage, a fast-speeding current, howling winds, large tides—and beneath all of these things a sudden, dangerous, confusion-causing shallowing. When these conditions all combine—then the waters begin to eddy and swirl, vortices are formed, immense sounds begin to thunder, spray fills the air, and all around the region notices are posted to warn sailors that to pass through this or that at flood or the ebb is at your direst peril.
Read the full article here. Highly recommended!