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A whirlpool is a swirling body of water produced by the meeting of opposing currents. The vast majority of whirlpools are not very powerful. More powerful ones may be termed ''maelstroms''. ''Vortex'' is the proper term for any whirlpool that has a downdraft. Whirlpools in oceans are usually caused by tides. Very small whirlpools can easily be seen when a bath or a sink is draining, but these are produced in a very different manner from those in nature. Smaller whirlpools also appear at the base of many waterfalls. In the case of powerful waterfalls, like Niagara Falls, these whirlpools can be quite strong. The most powerful whirlpools are created in narrow, shallow straits with fast flowing water. ==Notable whirlpools== Some of the most notable whirlpools in the world are the Saltstraumen in Norway, which reaches speeds of ; the Moskstraumen also in Norway (the original maelstrom), which reaches speeds of ; the Old Sow in Canada, which has been measured with a speed of up to ; the Naruto whirlpools in Japan, which have a speed of ; and the Corryvreckan in Scotland, which reaches speeds of . Powerful whirlpools have killed unlucky seafarers, but their power tends to be exaggerated by laymen. There are virtually no stories of large ships ever being sucked into a whirlpool. Tales like those by Paul the Deacon, Edgar Allan Poe, and Jules Verne are entirely fictional.〔Paul the Deacon, ''History of the Lombards'' (8th century AD); Edgar Allan Poe, "A Descent into the Maelström" (1841); and Jules Verne, ''Twenty Thousand Leagues Under the Sea'' (1870).〕 There was a short-lived whirlpool that sucked in a portion of Lake Peigneur in Louisiana, United States after a drilling mishap in 1980. This was not a naturally-occurring whirlpool, but a man-made disaster caused by breaking through the roof of a salt mine. The lake then behaved like a gigantic bathtub being drained, until the mine filled and the water levels equalized. A more recent example of a man-made whirlpool that received significant media coverage was in early June 2015, when an intake vortex formed in Lake Texoma, on the Oklahoma–Texas border, near the floodgates of the dam that forms the lake. At the time of the whirlpool's formation, the lake was being drained after reaching its highest level ever. The Army Corps of Engineers, which operates the dam and lake, expected that the whirlpool would last until the lake reached normal seasonal levels by late July. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「whirlpool」の詳細全文を読む スポンサード リンク
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