Whirlpool

A whirlpool is a body of swirling water produced by the meeting of opposing currents. The vast majority of whirlpools are not very powerful and very small whirlpools can easily be seen when a bath or a sink is draining. More powerful ones in seas or oceans may be termed maelstroms. Vortex is the proper term for any whirlpool that has a downdraft.

In oceans, in narrow straits, with fast flowing water, whirlpools are normally caused by tides; there are few stories of large ships ever being sucked into such a maelstrom, although smaller craft are in danger. Smaller whirlpools also appear at the base of many waterfalls and can also be observed downstream from manmade structures such as weirs and dams. In the case of powerful waterfalls, like Niagara Falls, these whirlpools can be quite strong.

Moskstraumen is an unusual system of whirlpools in the open seas in the Lofoten Islands off the Norwegian coast. It is the second strongest whirlpool in the world with flow currents reaching speeds as high as 32 km/h (20 mph). It finds mention in several books and movies.

The Moskstraumen is formed by the combination of powerful semi-diurnal tides and the unusual shape of the seabed, with a shallow ridge between the Moskenesøya and Værøy islands which amplifies and whirls the tidal currents.

The fictional depictions of the Maelstrom by Edgar Allan Poe and Jules Verne describe it as a gigantic circular vortex that reaches the bottom of the ocean, when in fact it is a set of currents and crosscurrents with a rate of 18 km/h (11 mph). Poe described this phenomenon in his short story A Descent into the Maelstrom, which in 1841 was the first to use the word "maelstrom" in the English language; in this story related to the Lofoten Maelstrom, two fishermen are swallowed by the maelstrom while one survives miraculously.

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