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Tidal race (or tidal rapid) is a natural occurrence whereby a fast moving tide
Tide

Tides are the rising of Earth's ocean surface caused by the tidal forces of the Moon and the Sun acting on the oceans. Tides cause changes in the depth of the marine and estuary water bodies and produce oscillating currents known as tidal streams, making prediction of tides important for coastal navigation ....
 passes through a constriction resulting in the formation of wave
Wave

A wave is a disturbance that propagates through space and time, usually with transference of energy. While a mechanical wave exists in a medium , waves of electromagnetic radiation can travel through vacuum, that is, without a medium....
s, eddies
Eddy (fluid dynamics)

In fluid dynamics, an eddy is the swirling of a fluid and the reverse current created when the fluid flows past an obstacle. The moving fluid creates a space devoid of downstream-flowing fluid on the downstream side of the object....
 and hazardous currents
Ocean current

An ocean current is continuous, directed movement of ocean water. The currents are generated from the forces acting upon the water like the Earth's rotation, the wind, the temperature, salinity differences and the tide....
. The constriction can be a passage where the sides narrow, for example the Gulf of Corryvreckan
Gulf of Corryvreckan

The Gulf of Corryvreckan , also called the Strait of Corryvreckan, is a narrow strait between the islands of Jura, Scotland and Scarba, in Argyll and Bute, off the west coast of Scotland....
 and the Saltstraumen
Saltstraumen

Saltstraumen is a Sound with a strong Tide located in Nordland 30 km east of the city of Bod?, Norway. The narrow channel connects the outer Saltfjord with its extension, the large Skjerstadfjord....
 maelstrom
Maelstrom

A maelstrom is a very powerful whirlpool; a large, swirling body of water. A free vortex, it has considerable downdraft. The Nordic word was introduced into English by Edgar Allan Poe in his story "A Descent into the Maelstr?m" ....
, or an underwater obstruction (a reef
Reef

In nautical terminology, a reef is a Rock , bar , or other feature lying beneath the surface of the water .Many reefs result from abiotic processes?deposition of sand, wave erosion planning down rock outcrops, and other natural processes?but the best-known reefs are the coral reefs of tropical waters developed through biotic processes do...
 or rising seabed
Seabed

The seabed is the bottom of the ocean. At the bottom of the continental slope is the continental rise, which is caused by sediment cascading down the continental slope....
), such as is found at the Portland Race
Isle of Portland

The Isle of Portland is a limestone tied island, long by wide, in the English Channel. Portland is south of the resort of Weymouth, Dorset, forming the southernmost point of the county of Dorset, England....
.

In extreme cases, such as Skookumchuck Narrows
Skookumchuck Narrows

Skookumchuck Narrows forms the entrance of Sechelt Inlet on British Columbia's Sunshine Coast, British Columbia in Canada. Before broadening into Sechelt Inlet, all of its tidal rapid together with that of Salmon Inlet and Narrow Inlet must pass through Sechelt Rapids....
 in British Columbia
British Columbia

British Columbia is the westernmost of Canada's Provinces and territories of Canada and is famed for its natural beauty, as reflected in its Latin motto, Splendor sine occasu ....
, through which tides can travel at more than 17 knots
Knot (speed)

The knot is a unit of speed equal to one nautical mile per hour. Its kn abbreviation is preferred by American and Canadian maritime authorities, and by the Institute of Electrical and Electronics Engineers; however, the kt and kts abbreviations also are used....
, very large whirlpool
Whirlpool

A whirlpool is a swirling body of water usually produced by ocean tides. The vast majority of whirlpools are not very powerful. More powerful ones are more properly termed maelstroms....
s develop, which can be extremely hazardous to navigation.








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Tidal race (or tidal rapid) is a natural occurrence whereby a fast moving tide
Tide

Tides are the rising of Earth's ocean surface caused by the tidal forces of the Moon and the Sun acting on the oceans. Tides cause changes in the depth of the marine and estuary water bodies and produce oscillating currents known as tidal streams, making prediction of tides important for coastal navigation ....
 passes through a constriction resulting in the formation of wave
Wave

A wave is a disturbance that propagates through space and time, usually with transference of energy. While a mechanical wave exists in a medium , waves of electromagnetic radiation can travel through vacuum, that is, without a medium....
s, eddies
Eddy (fluid dynamics)

In fluid dynamics, an eddy is the swirling of a fluid and the reverse current created when the fluid flows past an obstacle. The moving fluid creates a space devoid of downstream-flowing fluid on the downstream side of the object....
 and hazardous currents
Ocean current

An ocean current is continuous, directed movement of ocean water. The currents are generated from the forces acting upon the water like the Earth's rotation, the wind, the temperature, salinity differences and the tide....
. The constriction can be a passage where the sides narrow, for example the Gulf of Corryvreckan
Gulf of Corryvreckan

The Gulf of Corryvreckan , also called the Strait of Corryvreckan, is a narrow strait between the islands of Jura, Scotland and Scarba, in Argyll and Bute, off the west coast of Scotland....
 and the Saltstraumen
Saltstraumen

Saltstraumen is a Sound with a strong Tide located in Nordland 30 km east of the city of Bod?, Norway. The narrow channel connects the outer Saltfjord with its extension, the large Skjerstadfjord....
 maelstrom
Maelstrom

A maelstrom is a very powerful whirlpool; a large, swirling body of water. A free vortex, it has considerable downdraft. The Nordic word was introduced into English by Edgar Allan Poe in his story "A Descent into the Maelstr?m" ....
, or an underwater obstruction (a reef
Reef

In nautical terminology, a reef is a Rock , bar , or other feature lying beneath the surface of the water .Many reefs result from abiotic processes?deposition of sand, wave erosion planning down rock outcrops, and other natural processes?but the best-known reefs are the coral reefs of tropical waters developed through biotic processes do...
 or rising seabed
Seabed

The seabed is the bottom of the ocean. At the bottom of the continental slope is the continental rise, which is caused by sediment cascading down the continental slope....
), such as is found at the Portland Race
Isle of Portland

The Isle of Portland is a limestone tied island, long by wide, in the English Channel. Portland is south of the resort of Weymouth, Dorset, forming the southernmost point of the county of Dorset, England....
.

In extreme cases, such as Skookumchuck Narrows
Skookumchuck Narrows

Skookumchuck Narrows forms the entrance of Sechelt Inlet on British Columbia's Sunshine Coast, British Columbia in Canada. Before broadening into Sechelt Inlet, all of its tidal rapid together with that of Salmon Inlet and Narrow Inlet must pass through Sechelt Rapids....
 in British Columbia
British Columbia

British Columbia is the westernmost of Canada's Provinces and territories of Canada and is famed for its natural beauty, as reflected in its Latin motto, Splendor sine occasu ....
, through which tides can travel at more than 17 knots
Knot (speed)

The knot is a unit of speed equal to one nautical mile per hour. Its kn abbreviation is preferred by American and Canadian maritime authorities, and by the Institute of Electrical and Electronics Engineers; however, the kt and kts abbreviations also are used....
, very large whirlpool
Whirlpool

A whirlpool is a swirling body of water usually produced by ocean tides. The vast majority of whirlpools are not very powerful. More powerful ones are more properly termed maelstroms....
s develop, which can be extremely hazardous to navigation.

Notable tidal races

  • Skookumchuck Narrows
    Skookumchuck Narrows

    Skookumchuck Narrows forms the entrance of Sechelt Inlet on British Columbia's Sunshine Coast, British Columbia in Canada. Before broadening into Sechelt Inlet, all of its tidal rapid together with that of Salmon Inlet and Narrow Inlet must pass through Sechelt Rapids....
     in British Columbia
    British Columbia

    British Columbia is the westernmost of Canada's Provinces and territories of Canada and is famed for its natural beauty, as reflected in its Latin motto, Splendor sine occasu ....
    , Canada
    Canada

    Canada is a country occupying most of northern North America, extending from the Atlantic Ocean in the east to the Pacific Ocean in the west and northward into the Arctic Ocean....
  • The Bitches
    The Bitches

    The Bitches are a tidal race and set of rocks between Ramsey Island and the west Wales coastline near St. Davids. It is a popular tourist destination and playspot for extreme sports enthusiasts such as whitewater kayakers and surfers....
     in Wales
    Wales

    native_name = Cymru|conventional_long_name = Wales|common_name = Wales|image_flag = Flag of Wales 2.svg|national_motto = ...
    , United Kingdom
    United Kingdom

    The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom , the UK or Britain,is a sovereign state located off the northwestern coast of continental Europe....
  • Falls of Lora
    Falls of Lora

    The Falls of Lora is a tidal race which forms at the mouth of Loch Etive when a particularly high tide runs out from the loch.The falls are generated when the tide level in the Firth of Lorne drops below the level of the water in Loch Etive as the tide goes out....
     in Scotland
    Scotland

    conventional_long_name = ScotlandAlba|common_name= Scotland|image_flag = Flag of Scotland.svg|flag_width = 130px...
    , United Kingdom
  • Portland Bill on the Isle of Portland
    Isle of Portland

    The Isle of Portland is a limestone tied island, long by wide, in the English Channel. Portland is south of the resort of Weymouth, Dorset, forming the southernmost point of the county of Dorset, England....
    , England
    England

    native_name =|conventional_long_name = England|common_name = England|image_flag = Flag of England.svg|image_coat = England COA.svg|symbol_type = Royal Coat of Arms...
    , United Kingdom


See also

  • Rip current
    Rip current

    A rip current, or rip is a strong surface flow of water returning seaward from near the shore . Although rip currents would exist even without the tides, tides can make an existing rip much more dangerous?especially low tide....
  • Tidal bore
    Tidal bore

    A tidal bore is a tide phenomenon in which the leading edge of the incoming tide forms a wave of water that travel up a river or narrow bay against the direction of the current....