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A strait is a water body connecting two seas or two water basins. While the landform generally constricts the flow, the surface water still flows, for the most part, at the same elevation on both sides and through the strait in both directions. In some straits there may be a dominant directional current through the strait. Most commonly, it is a narrowing channel that lies between two land masses. Some straits are not navigable, for example because they are either too narrow or too shallow, or because of an unnavigable reef or archipelago. Straits are also known to be loci for sediment accumulation. Usually, sand-size deposits occur on both the two opposite strait exits, forming subaqueous fans or deltas.
The terms channel , pass, or passage can be synonymous and used interchangeably with strait, although each is sometimes differentiated with varying senses. In Scotland, firth or Kyle are also sometimes used as synonyms for strait.
Many straits are economically important. Straits can be important shipping routes and wars have been fought for control of them.
Numerous artificial channels, called canals , have been constructed to connect two oceans or seas over land, such as the Suez Canal. Although rivers and canals often provide passage between two large lakes, and these seem to suit the formal definition of strait, they are not usually referred to as such. Rivers and often canals, generally have a directional flow tied to changes in elevation, whereas straits often are free flowing in either direction or switch direction, maintaining the same elevation. The term strait is typically reserved for much larger, wider features of the marine environment. There are exceptions, with straits being called canals; Pearse Canal, for example.
Straits are the converse of isthmuses. That is, while a strait lies between two land masses and connects two large areas of ocean, an isthmus lies between two areas of ocean and connects two large land masses.
Some straits have the potential to generate significant tidal power using tidal stream turbines. Tides are more predictable than wave power or wind power. The Pentland Firth (a strait) may be capable of generating 10 GW. [1] Cook Strait in New Zealand may be capable of generating 5.6 GW [2] even though the total energy available in the flow is 15 GW. [3]
Straits used for international navigation through the territorial sea between one part of the high seas or an exclusive economic zone and another part of the high seas or an exclusive economic zone are subject to the legal regime of transit passage (Strait of Gibraltar, Dover Strait, Strait of Hormuz). The regime of innocent passage applies in straits used for international navigation (1) that connect a part of high seas or an exclusive economic zone with the territorial sea of a coastal nation (Straits of Tiran, Strait of Juan de Fuca, Strait of Baltiysk) and (2) in straits formed by an island of a state bordering the strait and its mainland if there exists seaward of the island a route through the high seas or through an exclusive economic zone of similar convenience with respect to navigational and hydrographical characteristics (Strait of Messina, Pentland Firth). There may be no suspension of innocent passage through such straits. [4]
The Dardanelles, also known as the Strait of Gallipoli and in Classical Antiquity as the Hellespont, is a narrow, natural strait and internationally significant waterway in northwestern Turkey that forms part of the continental boundary between Asia and Europe and separates Asian Turkey from European Turkey. Together with the Bosporus, the Dardanelles forms the Turkish Straits.
The Strait of Gibraltar is a narrow strait that connects the Atlantic Ocean to the Mediterranean Sea and separates Europe from Africa. The two continents are separated by 7.7 nautical miles at its narrowest point. Ferries cross between the two continents every day in as little as 35 minutes. The Strait's depth ranges between 300 and 900 metres.
The Strait of Malacca is a narrow stretch of water, 800 kilometres (500 mi) long and from 65 to 250 km wide, between the Malay Peninsula to the northeast and the Indonesian island of Sumatra to the southwest, connecting the Andaman Sea and the South China Sea. As the main shipping channel between the Indian and Pacific oceans, it is one of the most important shipping lanes in the world.
The Bab-el-Mandeb, the Gate of Grief or the Gate of Tears, is a strait between Yemen on the Arabian Peninsula and Djibouti and Eritrea in the Horn of Africa. It connects the Red Sea to the Gulf of Aden and by extension the Indian Ocean.
Cook Strait is a strait that separates North Island from the South Island of New Zealand. The strait connects the Tasman Sea on the northwest with the South Pacific Ocean on the southeast. It is 22 kilometres (14 mi) wide at its narrowest point, and is considered one of the most dangerous and unpredictable waters in the world. Regular ferry services run across the strait between Picton in the Marlborough Sounds and Wellington.
Firth is a word in the English and Scots languages used to denote various coastal waters in the United Kingdom, predominantly within Scotland. In the Northern Isles, it more often refers to a smaller inlet. It is linguistically cognate to Scandinavian fjord and fjard, with the original meaning of "sailable waterway". The word has a more constrained sense in English. Bodies of water named "firths" tend to be more common on the Scottish east coast, or in the southwest of the country, although the Firth of Clyde is an exception to this. The Highland coast contains numerous estuaries, straits, and inlets of a similar kind, but not called "firth" ; instead, these are often called sea lochs. Before about 1850, the spelling "Frith" was more common.
An isthmus is a narrow piece of land connecting two larger areas across an expanse of water by which they are otherwise separated. A tombolo is an isthmus that consists of a spit or bar, and a strait is the sea counterpart of an isthmus, a narrow stretch of sea between two landmasses that connects two larger bodies of water.
The Strait of Dover or Dover Strait, historically known as the Dover Narrows, is the strait at the narrowest part of the English Channel, marking the boundary between the Channel and the North Sea, and separating Great Britain from continental Europe. The shortest distance across the strait, at approximately 20 miles, is from the South Foreland, northeast of Dover in the English county of Kent, to Cap Gris Nez, a cape near to Calais in the French département of Pas-de-Calais. Between these points lies the most popular route for cross-channel swimmers. The entire strait is within the territorial waters of France and the United Kingdom, but a right of transit passage under the United Nations Convention on the Law of the Sea allows vessels of other nations to move freely through the strait.
The Pentland Firth is a strait which separates the Orkney Islands from Caithness in the north of Scotland. Despite the name, it is not a firth.
The Sunda Strait is the strait between the Indonesian islands of Java and Sumatra. It connects the Java Sea with the Indian Ocean.
The Lombok Strait, is a strait of the Bali Sea connecting to the Indian Ocean, and is located between the islands of Bali and Lombok in Indonesia. The Gili Islands are on the Lombok side.
Wetar Strait is an international strait in Southeast Asia. It separates the island of Wetar from the eastern part of the island of Timor. The strait is also the eastern portion of a pair of international straits, the other one being Ombai Strait; the two straits combine to link the Indian Ocean with the Pacific Ocean.
The Turkish Straits are two internationally significant waterways in northwestern Turkey. The Straits create a series of international passages that connect the Aegean and Mediterranean seas to the Black Sea. They consist of the Dardanelles and the Bosphorus. The straits are on opposite ends of the Sea of Marmara. The straits and the Sea of Marmara are part of the sovereign sea territory of Turkey and are treated as Turkish internal waters.
New Zealand has large ocean energy resources but does not yet generate any power from them. TVNZ reported in 2007 that over 20 wave and tidal power projects are currently under development. However, not a lot of public information is available about these projects. The Aotearoa Wave and Tidal Energy Association was established in 2006 to "promote the uptake of marine energy in New Zealand". According to their 10 February 2008 newsletter, they have 59 members. However, the association doesn't list its members.
Transit passage is a concept of the law of the sea, which allows a vessel or aircraft the freedom of navigation or overflight solely for the purpose of continuous and expeditious transit of a strait between one part of the high seas or exclusive economic zone and another. The requirement of continuous and expeditious transit does not preclude passage through the strait for the purpose of entering, leaving or returning from a state bordering the strait, subject to the conditions of entry to that state. The transit passage may be exercised regardless of the nationality (flag) of the ship, its form of ownership, the merchant or government status of a ship or warship, the private or government status of an aircraft.
Dynamic tidal power or DTP is an untried but promising technology for tidal power generation. It would involve creating a long dam-like structure perpendicular to the coast, with the option for a coast-parallel barrier at the far end, forming a large 'T' shape. This long T-dam would interfere with coast-parallel tidal wave hydrodynamics, creating water level differences on opposite sides of the barrier which drive a series of bi-directional turbines installed in the dam. Oscillating tidal waves which run along the coasts of continental shelves, containing powerful hydraulic currents, are common in e.g. China, Korea, and the UK.
A tidal stream generator, often referred to as a tidal energy converter (TEC), is a machine that extracts energy from moving masses of water, in particular tides, although the term is often used in reference to machines designed to extract energy from the run of a river or tidal estuarine sites. Certain types of these machines function very much like underwater wind turbines and are thus often referred to as tidal turbines. They were first conceived in the 1970s during the oil crisis.
A gat is an inshore channel or strait connecting coastal waters with the open sea or dividing two landmasses, such as two islands or an island and a peninsula. Gats are usually relatively narrow but deep and are in many instances constantly eroded by currents flowing back and forth, such as tidal currents. The term is mostly used for features on the North Sea and Baltic Sea coasts.
An international strait is a narrow natural waterway connecting two parts of the high seas or exclusive economic zones, used for international navigation. Per the United Nations Convention on the Law of the Sea (UNCLOS), a transit passage regime prevails in such straits for both ships and aircraft with few exceptions, even when the territorial waters of bordering country or countries overlap. Worldwide, more than 200 straits might satisfy the criteria of an international strait. Notable international straits include Bosporus and Dardanelles, Strait of Magellan, Strait of Gibraltar, Strait of Dover, and Danish straits, with the most famous being probably the Strait of Hormuz.
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