Editing Sneaker wave

{{short description|Disproportionately large coastal wave}}
{{Use dmy dates|date=September 2020}}
[[File:Sneaker wave.jpg|thumb|Sneaker wave at [[Bolinas, California]]]]
A '''sneaker wave''', also known as a '''sleeper wave''', or in [[Australia]] as a '''king wave''', is a disproportionately large coastal wave that can sometimes appear in a [[wave train]] without warning.

==Terminology==
The term "sneaker wave" is popular rather than scientific, derived from the observation that such a wave can "sneak up" on an unwary beachgoer. There is no scientific coverage of the phenomenon as a distinct sort of wave with respect to height or predictability as there is on other extreme wave events such as [[tsunami]]s or [[rogue wave]]s, and little or no scientific evidence has been gathered to identify, describe, or define sneaker waves. Although the term "rogue wave" — meaning an unusually tall or steep wave in mid-ocean — is sometimes used as a synonym for "sneaker wave," one American oceanographer distinguishes "rogue waves" as occurring on the ocean and "sneaker waves" as occurring at the shore,<ref>{{Cite web
| url=https://www.kqed.org/science/10197/what-makes-sneaker-waves-so-sneaky-and-dangerous
| title=What Makes 'Sneaker Waves' so Sneaky -- and Dangerous
| first=Craig
| last=Miller
| date=22 October 2013
| publisher=[[KQED Inc.|KQED]]
| access-date=2020-07-13}}</ref> while the [[National Oceanic and Atmospheric Administration]] loosely defines rogue waves as offshore waves that are at least twice the height of surrounding waves and sneaker waves as waves near shore that are unexpectedly and significantly larger than other waves reaching shore at the time.<ref name=cnn20100215>[http://www.cnn.com/2010/US/02/15/rogue.wave/index.html Johnson, Craig, and Jason Hanna, "Waves that injured surf audience were sneaky, but not 'rogue'," CNN, February 15, 2010 Accessed 4 December 2021]</ref> Scientists do not yet understand what causes sneaker waves,<ref name=tomlinson20210401>[https://thatoregonlife.com/2021/04/what-you-dont-know-about-oregon-coast-sneaker-waves-could-kill-you/ Tomlinson, Jessica, "What You Don’t Know About Oregon Coast Sneaker Waves Could Kill You," That Oregon Life, April 1, 2021 Accessed 4 December 2021]</ref> and their relationship to rogue waves, if any, has not been established.

In a 2018 paper, [[Oregon State University]] researchers wrote that sneaker waves form in offshore storms that transfer wind energy to the ocean surface. The resulting waves then arrive along a coastline during periods of calm weather, and the greater amount of energy they contain compared to the regular waves that preceded them causes them to travel far higher up the shore than the other waves.<ref>[https://www.kron4.com/news/california/parents-of-boy-swept-to-sea-didnt-know-about-the-hidden-dangers-of-californias-sneaker-waves/ Anonymous, "Parents of boy swept to sea didn’t know about the hidden dangers of California’s sneaker waves," Nexstar Media Inc. via the Associated Press, May 4, 2021 Accessed 4 December 2021]</ref> As of 2021, the [[National Weather Service]] in the [[United States]] viewed ocean conditions along the [[United States West Coast]] as favorable for sneaker waves when an offshore storm generates waves with a particularly long period — perhaps longer than 15 seconds — between swells, allowing the swells to build considerable force before reaching shore, where they might appear either as conventional large waves or as sneaker waves.<ref>[https://www.beachconnection.net/news/sneakwav100121.php "Caution Urged on Oregon Coast: Sneaker Wave Dangers This Weekend," Oregon Coast Beach Connection, October 1, 2021 Accessed 4 December 2021]</ref>

==Characteristics==

Sneaker waves appear suddenly on a coastline and without warning;<ref name=nwssneakerwaveslogrolls>[https://www.weather.gov/safety/ripcurrent-waves "Sneaker/High Waves and Log Rolls Can Be Deadly," National Weather Service Accessed 4 December 2021]</ref> generally, it is not obvious that they are larger than other waves until they break and suddenly surge up a beach. A sneaker wave can occur following a period of 10 to 20 minutes of gentle, lapping waves.<ref name=nwssneakerwaveslogrolls/> Upon arriving, a sneaker wave can surge more than {{convert|150|ft|-1}} beyond the foam line, rushing up a beach with great force.<ref name=nwssneakerwaveslogrolls/> In addition to containing a large volume of rapidly surging water, a sneaker wave also tends to carry a large amount of sand and gravel with it. It can be strong enough to break over rocks and float or roll large, waterlogged logs lying on the beach weighing several hundred [[Pound_(mass)|pound]]s, moving them up the beach during the landward surge and then back down toward the ocean as the wave retreats.<ref name=nwssneakerwaveslogrolls/> Sneaker waves appear to be more common along steep coastlines than in areas with broader, more gently sloped beaches.<ref name=nwssneakerwaveslogrolls/>

==Hazards==

The unpredictability of sneaker waves and their tendency to arrive suddenly after lengthy periods of gentle, lapping waves makes it easy for them to surprise unwary or inexperienced beachgoers;<ref name=nwssneakerwaveslogrolls/> because they are much larger than preceding waves, sneaker waves can catch inattentive [[human swimming|swimmers]], waders, and other people on beaches and ocean [[Jetty|jetties]] and wash them into the sea. The force of a sneaker wave's surge and the large volume of water rushing far up a beach is enough to suddenly submerge people thigh- or waist-deep, knock them off their feet, and drag them into the ocean or trap them against rocks.<ref name=nwssneakerwaveslogrolls/> Many coastlines more prone to sneaker waves lie in colder parts of the world where beachgoers tend to wear heavier clothing; the amount of [[sand]] and [[gravel]] in a sneaker wave can quickly fill such clothing and footwear such as boots with [[sediment]] that weighs a person down as he or she is swept up a beach and then back into the sea, increasing the chances of drowning.<ref name=nwssneakerwaveslogrolls/> Floating and rolling logs in a sneaker wave also pose a danger, as they can badly injure people as well as pin people down when they come to rest, and it can be difficult or impossible to move such a log before a person pinned by it drowns as later waves arrive and fill the person's lungs with water and sediment.<ref name=nwssneakerwaveslogrolls/>

==Geographic distribution==
Sneaker waves are mainly referred to in warnings and reports of incidents for the coasts of [[Central Coast (California)|Central]] and [[Northern California|Northern]] [[California]] (including the [[San Francisco]] [[San Francisco Bay Area|Bay Area]]'s beaches, especially [[Ocean Beach, San Francisco|Ocean Beach]],<ref>{{cite news 
|title=California's deadliest beach is in the Bay Area 
|author=Ted Andersen 
|url=https://www.sfgate.com/bayarea/article/California-s-deadliest-beach-is-in-the-Bay-Area-13245629.php 
|newspaper=[[San Francisco Chronicle]] 
|date=28 September 2018 
|access-date=10 August 2020}}</ref> [[Baker Beach]],<ref>{{cite news 
|title=Teen Swept Away by 'Rogue' Wave / Boy was at Baker Beach posing for a picture 
|author=Malcolm Glover and Dan Levy 
|url=https://www.sfgate.com/news/article/Teen-Swept-Away-by-Rogue-Wave-Boy-was-at-2719914.php 
|newspaper=San Francisco Chronicle 
|date=23 December 2000 
|access-date=10 August 2020}}</ref> and those that face the [[Pacific Ocean]],<ref>{{cite news 
|title=Sneaker wave danger at Bay Area beaches: 'Never turn your back to the ocean' 
|author=Amy Graff 
|url=https://www.sfgate.com/weather/article/Sneaker-wave-danger-Bay-Area-beach-hazard-14991703.php 
|newspaper=San Francisco Chronicle |date=21 January 2020 
|access-date=10 August 2020}}</ref> e.g. from [[Big Sur]] to the California–[[Oregon]] border), Oregon, and [[Washington (state)|Washington]] in the [[Western United States|Western]] [[United States]].<ref>{{Cite web
| title=Sleeper waves have led to other drownings in Humboldt County beaches
| url=https://www.sfgate.com/bayarea/article/HUMBOLDT-COUNTY-Beach-where-2-died-has-deadly-2467720.php
| work=San Francisco Chronicle
| date=2006-10-24
| access-date=2020-08-01}}</ref><ref>{{Cite web
| title=Rogue or Sneaker Waves
| url=https://marydonahue.org/rogue-or-sneaker-waves
| publisher=Mary Donahue
| access-date=2020-08-01}}</ref><ref>{{Cite web
| title=Dangerous Sneaker waves possible on Central Coast
| url=https://kion546.com/news/2019/12/26/dangerous-sneaker-waves-possible-on-central-coast/
| publisher=KION5/46
| date=2019-12-26
| access-date=2020-08-01}}</ref><ref>{{Cite web
| title=Sneaker/High Waves and Log Rolls Can Be Deadly
| url=https://www.weather.gov/safety/ripcurrent-waves
| publisher=[[National Weather Service]]
| access-date=2020-07-13}}</ref><ref>{{Cite web
| url=https://www.nps.gov/pore/planyourvisit/safety_beaches.htm
| title=Safety Issues Associated with Beaches
| publisher=[[National Park Service]]}}</ref><ref>{{Cite web
| url=https://newportoregon.gov/dept/npd/pdfs/New_Residents_Welcome_to_Newport.pdf
| title=New Residents: Welcome to Newport
| date=2018-04-17
| publisher=[[Newport, Oregon]] Police Department
| access-date=2020-07-13}}</ref> Sneaker waves also occur on the coast of [[British Columbia]] in [[Western Canada|Western]] [[Canada]], especially the province's southern coast, because they commonly occur on the west coast of [[Vancouver Island]] (including [[Tofino]], [[Ucluelet]], and [[Cape Scott Provincial Park]]).<ref>{{Cite web
| title=Cape Scott Provincial Park: Hiking
| url=http://bcparks.ca/explore/parkpgs/cape_scott/hiking.html
| access-date=2020-07-28}}</ref><ref>{{Cite web
| title=Hiking and Outdoor Safety
| url=https://www.tofinohiking.com/safety/
| access-date=2020-07-16}}</ref><ref>{{Cite web
| title=Dangerous Sneaker Waves
| date=18 April 2016
| url=https://oregondiscovery.com/sneaker-waves
| access-date=2020-07-20}}</ref><ref>{{Cite web
| title=Giant wave crashes into Tofino resort's oceanfront
| url=https://globalnews.ca/video/3974609/giant-wave-crashes-into-tofino-resorts-oceanfront
| format=video
| date=2018-01-18
| access-date=2020-07-13}}</ref> Sneaker waves are common on the southern coast of [[Iceland]], and warning signs were erected at Reynisfjara and Kirkjufjara beaches, following three unrelated tourist deaths at those beaches over several years, the third of them in January 2017.<ref>{{cite web
| title="Terrible situation" at Iceland's Reynisfjara beach - security to be improved
| url=https://icelandmonitor.mbl.is/news/nature_and_travel/2017/01/12/terrible_situation_at_iceland_s_reynisfjara_beach_s/
| website=Iceland Monitor
| date=2017-01-12
| access-date=2020-07-13}}</ref> In [[Australia]], where they are known as "king waves," sneaker waves occur especially in [[Western Australia]] and [[Tasmania]], where they can be a hazard for rock fishermen.<ref>{{cite web
| url=https://www.abc.net.au/news/2011-05-12/king-wave-almost-claims-more-at-salmon-holes/2709614
| title=King wave almost claims more at Salmon Holes
| date=2011-05-12
| publisher=[[ABC News (Australia)]]
| access-date=2020-07-13}}</ref>

Along much of the [[United States West Coast]], sneaker waves kill more people than all other weather hazards combined.<ref name=nwssneakerwaveslogrolls/> In Oregon, 21 deaths were attributed to sneaker waves from 1990 through March 2021,<ref name=tomlinson20210401/> most of the deaths occurring between October and April, although sneaker waves also occurred at other times of year.<ref name=tomlinson20210401/>

A sneaker wave incident gained worldwide media attention when two large waves suddenly and unexpectedly struck a crowd watching the [[Titans of Mavericks|Mavericks surfing competition]] at [[Mavericks, California|Mavericks]] in [[Princeton-by-the-Sea, California|Princeton-by-the-Sea]], California, on February 13, 2010, breaking over a [[seawall]] onto a narrow beach and injuring at least 13 people.<ref name=cnn20100215/><ref>[https://www.cbsnews.com/news/surfing-spectators-struck-by-50-foot-wave/ Blackstone, John, "Surfing Spectators Struck by 50-Foot Wave," CBS News, February 14, 2021 Accessed 4 December 2021]</ref> The incident was caught on film.<ref name=cnn20100215/><ref>[https://www.youtube.com/watch?v=FPdq-QAB-cU ketchdust, "Mavericks February 13 2010 Rogue Wave," Youtube, Accessed 31 December 2023]</ref>

In March 2014, a massive wave struck [[Roi-Namur]] in [[Kwajalein Atoll]] in the [[Marshall Islands]] on an otherwise calm, sunny day, penetrating well inland, flooding parts of the island and swamping coastal roads.<ref>{{Cite web|url=https://www.nationalgeographic.com/news/2018/04/marshall-islands-climate-change-floods-waves-environment-science-spd/|archive-url=https://web.archive.org/web/20190825132031/https://www.nationalgeographic.com/news/2018/04/marshall-islands-climate-change-floods-waves-environment-science-spd/|url-status=dead|archive-date=August 25, 2019|title=Within Decades, Floods May Render Many Islands Uninhabitable|last=Greshko|first=Michael|date=2018-04-25|website=National Geographic News|access-date=2019-08-25}}</ref>

On September 18, 2023, a sneaker wave smashed into a beachside restaurant at [[Marina Beach, KwaZulu-Natal|Marina Beach]] near [[Southbroom]], [[South Africa]], injuring seven people. One restaurant patron was swept out to sea but rescued by [[lifeguard]]s. The wave was filmed.<ref>{{cite news| url=https://www.iol.co.za/dailynews/news/look-several-people-injured-after-wave-crashes-into-a-restaurant-at-marina-beach-38b248d4-7cf5-4204-80f1-8b13d08ed191 | last=Ngema |first= Thobeka  | work=IOL | title= Several people injured after wave crashes into a restaurant at Marina Beach | date=18 September 2023 | access-date=24 October 2023}}</ref>

[[Rio de Janeiro]]'s [[Barra de Tijuca]] beach in [[Brazil]] experiences sneaker waves, known locally as ''ressaca'' waves. It also is a steep beach and a December 2023 news film shows the whole beach being cleared by a sneaker wave.{{citation needed|date=January 2024}}

On 20 January 2024, one or more sneaker or [[rogue wave]]s struck the [[United States Army]]′s [[Ronald Reagan Ballistic Missile Defense Test Site]] on [[Roi-Namur]] in [[Kwajalein Atoll]] in the [[Marshall Islands]], breaking down the doors of a dining hall, knocking several people off their feet, moderately to severely damaging the dining hall, the Outrigger Bar and Grill, the chapel, and the Tradewinds Theater, and leaving parts of the island, including the automotive complex, underwater. The flooding of the dining hall was filmed. The wave or waves penetrated {{convert|300|ft|-2}} inland and probably were between {{convert|29|and|40|ft}} tall amid a significant wave height of {{convert|10|ft|0}} to {{convert|15|ft|0}}.<ref>{{cite news|url=https://www.washingtonpost.com/weather/2024/01/25/rogue-wave-marshall-islands-military-base/|title=Massive waves slammed a U.S. Army base. How it happened is mysterious|author=Matthew Cappucci|newspaper=The Washington Post|date=January 25, 2024|access-date=January 26, 2024}}</ref>

==Seventh wave==
In many parts of the world, local [[folklore]] predicts that out of a certain number of waves, one will be much larger than the rest. "Every seventh wave" or "every [[The Ninth Wave|ninth wave]]" are examples of such common beliefs that have wide circulation and have entered popular culture through music, literature, and art.<ref>{{Cite book
| first=Blair
| last=Kinsman
| title=Wind Waves: Their Generation and Propagation on the Ocean Surface
| date=1984
| publisher=[[Dover Publications]]
| page=10
| isbn=9780486495118}}</ref><ref>{{cite web
| url=http://framing.indiana.edu/2015/01/05/debating-globalization-ninth-wave/
| title=Debating Globalization and the Ninth Wave
| first=Rosemary
| last=Pennington
| date=2015-01-15
| publisher=[[Indiana University]]
| archive-url=https://web.archive.org/web/20191129041823/http://framing.indiana.edu/2015/01/05/debating-globalization-ninth-wave/
| archive-date=2019-11-29
| url-status=dead}}</ref> These ideas have some scientific merit, due to the occurrence of wave groups at sea,<ref>{{Cite book
| author=Massel, Stanislaw R.
| title=Ocean surface waves: their physics and prediction
| date=1996
| publisher=World Scientific
| location=Singapore
| chapter=4.6
| pages=192–200
| isbn=9789810221096}}</ref> but there is no explicit evidence for this specific phenomenon, or that these wave groups are related to sneaker waves. The saying is likely derived more from a cultural fascination with certain numbers,{{citation needed|date=January 2020}} and it may also be designed to educate shore-dwellers about the necessity of remaining vigilant when near the ocean.

==See also==
{{portal|Oceans}}
* [[Wind wave]]
* [[Rogue wave]]
* [[Tsunami]]
* [[Megatsunami]]
* [[Meteotsunami]]

==References==
{{reflist}}

==External links==
* {{YouTube|id=RPypT9dOvSY|title=Sneaker wave south of Coos Bay: Caught on camera}} - Video of a sneaker wave off the Oregon coast

[[Category:Water waves]]
[[Category:Weather hazards]]