The sea is a relatively small part of the ocean, which protrudes into the land, is separated from the ocean by the shores of islands, continents and peninsulas. The seas differ from other parts of the ocean in that there is an individual water temperature, salinity and a peculiar geological structure bottom. The seas are divided according to the features of their location relative to land into interisland, marginal and inland. Inland seas include intercontinental and intracontinental.

Inland seas are places that go deep into the land and are connected by one or a pair of straits with the ocean. Since the seas are quite difficult to communicate with the ocean, their waters have their own characteristics. Let us give an example of inland seas, which include the White, Baltic, Black and Azov Seas.
Intercontinental seas are located between two continents (continents). Such seas, for example, are the Red and Mediterranean Seas, both of these seas are located between Africa and Eurasia.

The seas that are separated by islands from the ocean or adjoin the mainland are called marginal. Such seas have a direct connection with the ocean, so their water properties are very similar to the surrounding areas. open ocean. Such seas include, for example, the Kara, Barents and Chukchi Seas.

Interisland seas are located among island archipelagos or large islands. Such seas are considered Java, Fiji and the Banda Sea. In the center of Eurasia are the Aral and Caspian Seas, they are completely separated from the World Ocean and, in fact, should be considered salt lakes. They are called seas only because of their large size.

Parts of the ocean that go deep into the land and freely communicate with the ocean itself are called bays. For example, the Bays of Biscay and Guinea of ​​the Atlantic Ocean, or the Bay of Bengal, extending from the Indian Ocean. In terms of their hydrological properties, the bays practically do not differ from the nearby areas of the oceans and seas.

Some geographical part of the bays, for example, Hudson and Persian, should be considered as seas, and vice versa, some seas, for example, Beaufort, would be more correctly considered as a bay. However, these trivial names were historically formed and they were so firmly attached to these geographical objects that now it is hardly possible to rename them. Oceans, seas and bays are also interconnected by straits.

Straits are such relatively narrow bodies of water that separate two areas of land. The width of a strait is the distance between two pieces of land separated by water, and the length of a strait is the distance from the current to the next major body of water. The Drake Passage, an unusually wide almost 1 thousand kilometers, it connects the Pacific and Atlantic oceans. The Strait of Gibraltar, on the contrary, was quite narrow at one time, and connecting the Atlantic Ocean with the Mediterranean Sea, at its narrowest point it is only 14 kilometers wide. The Mozambique Strait is considered the longest strait, its length is 1760 kilometers.

The bottom of the Coral Sea, located in the southwestern Pacific Ocean, as well as small islands and shallow waters are covered with coral colonies. The western part of the sea has the most grandiose building on Earth that has ever been created by living organisms - the Barrier Reef. This reef has a length of 2300 kilometers along the Australian coast.

The Sargasso Sea does not have solid shores, as it is located in the central part of the largest ocean currents, such as the Florida, North Equatorial and Gulf Stream currents. In the calm and warm water of the sea, widespread algae - Sargasso live. From the name of these algae came the name of the sea itself. Large accumulations of algae give the viewer the impression that this is a large boundless ocean meadow - such an accumulation of algae is a real paradise for many living inhabitants of the sea.

Today there are 81 seas.

All seas are divided according to their location in the following directions: Atlantic, Pacific, inland seas and seas, with the Southern Ocean, North and Indian Ocean.

Sea views

Seas are traditionally divided into four groups:
- interisland,
- semi closed
- marginal,
- internal.

Inland seas are "inside" the continents, but may be connected to the ocean or other adjacent sea. Such seas are subject to a great influence of the land, the water in them may have a variable level. These seas include: the Dead Sea, the Aral Sea and the Caspian Sea.

Some scientists and researchers consider the coastal sea, and therefore they do not include inland seas, interisland seas in the general list.

The marginal seas are located on the edge of the land and have direct access to the ocean, but the semi-enclosed seas are fenced off by the mainland, but partially.

Interisland seas, based on the basis of their name, are located between different islets. The inter-island seas include the following: Fiji, the Java Sea and the New Guinea Sea.

Lack of seas

Compared to land and land in general, the area of ​​\u200b\u200bthe seas on the planet is small. There is even a garbage sea, which, due to the large amount of waste, turns into a floating garbage dump that pollutes the world's oceans. Such seas of plastic and other waste have been observed in the waters of the Indian and Pacific Oceans.

It is worth mentioning the disappearing seas. For example, the huge Aral Sea due to the influence economic activity man began to disappear, the water seemed to evaporate. And all this happened due to water intake from other rivers, so fresh water stopped flowing into the Aral Sea. As a result, all the fauna that lived in this once vast sea simply disappeared, the climate of the area changed: where gardens previously bloomed and the breeze blew, today there are only desert dunes and skeletons of ships rotted from time to time. This terrible tragedy of the region, which has not gone unnoticed in the world. Attempts were made to artificially resurrect the sea, but they were in vain. After more than half a century, it became obvious that only natural forces are able to restore the original balance of water and land, today the sea is slowly coming to life.

The issue of environmental situation and the issue of safety water resources every year it becomes more and more acute: scientists suggest that climate change and the active expansion of man into the natural elements will wipe out more than one sea from the face of the planet, and the war between nations is not far off, not for territory, but for fresh and salt water.

How many seas are on earth? Nobody can tell you the exact answer. For example, the International Hydrographic Bureau identifies only 54 seas, some scientists believe that there are more than 90 seas on our planet (not counting the Caspian, Dead and Galilee, which are often referred to as lakes). The most common version is that there are still 81 seas. Such a discrepancy arises due to the fact that scientists interpret the very concept of "sea" in different ways.

The most common interpretation: sea ​​- a body of water separated by parts of land or elevations of underwater relief . From a geological point of view, the seas are young formations. The deepest formed at the break tectonic plates such as the Mediterranean. Smaller ones are formed on the outskirts of the continents when the continental shoals are flooded.

Characteristics of the seas

The seas are actively involved in the creation of the temperature regime the globe. Sea water very "lazy" and heats up slowly. Therefore, for example, the water in the Mediterranean Sea becomes warmest not in July, when it is hot, but in September. As the level drops, the water cools down quickly. At the bottom of the deepest seas - about 0ºC. While freezing salty water starts at -1.5 ºC; - 1.9 ºC.

Warm and cold currents move huge masses of water - warm or cold. This greatly affects the formation of the climate.

An important role is also played by the ebbs and flows, the frequency of their change and height. The occurrence of ebbs and flows is associated with a change in the phases of the moon.

Known interesting feature water in the sea. When immersed, the sea gradually "eats" the colors. At a depth of 6 m, scarlet colors disappear, at a depth of 45 m - orange, 90 m - yellow, at a depth of more than 100 m only purple and greenish shades remain. Therefore, the most colorful underwater world is located at shallow depths.

Sea types

There are several classifications that unite the seas according to certain criteria. Consider the most popular.

1. Over the oceans(list of seas by oceans)

2. By degree of isolation

Internal - do not have access to the ocean (isolated), or are connected with them through the straits (semi-isolated). In fact, isolated seas (Aral, Dead) are considered to be lakes. And the straits connecting the semi-isolated seas with the ocean are so narrow that they do not lead to mixing of deep waters. Example - Baltic, Mediterranean.

Marginal - located on the shelf, have an extensive network of underwater currents and free access to the ocean. They are separated from each other by islands or underwater hills.

Interisland - such seas are surrounded by a close group of islands that prevent connection with the ocean. Most of these seas among the islands of the Malay Archipelago are Javanese, Sulawesi.

Intercontinental - seas lying at the junction of continents - Mediterranean, Red.

3. According to the salinity of the waters distinguish slightly saline (Black) and highly saline (Red) seas.

4. By the degree of indentation of the coastline There are seas with a strongly indented and slightly indented coastline. But, for example, the Sargasso Sea has no coastline at all.

The coastlines are characterized by the presence of bays, estuaries, bays, spits, cliffs, peninsulas, beaches, fjords and headlands.

The difference between the sea and the lake, the bay and the ocean

Despite the great similarity of interpretations of the concepts "sea", "lake", "bay" and "ocean", these words are not synonymous.

So, the sea differs from the lake:

Size. The sea is always bigger.

The degree of salinity of the waters. In the sea, water is always mixed with salt, while in lakes it can be fresh, brackish and salty.

Geographic location. Lakes are always located within continents and are surrounded on all sides by land. The seas most often have a connection with the ocean.

It is more difficult to separate seas and oceans. It's all about size here. It is generally accepted that the sea is only a part of the ocean that has unique flora and fauna. The sea may differ from the ocean in the degree of salinity of the water and in relief.

The bay is also an integral part of the ocean, deeply incised into the land. Unlike the sea, it always has a free connection with the ocean. In some cases, the name of the bay was assigned to the water areas, which, according to their hydrological characteristics, are more likely to be seas. For example, Hudson Bay, California, Mexico.

The most salty sea

(The Dead Sea)

If we consider the Dead Sea as a sea, and not a lake, then the palm in terms of the degree of salinity of the waters will belong to this area. The salt concentration here is 340 g/l. Because of the salt, the density of the water is such that it is impossible to drown in the Dead Sea. By the way, this is why there are no fish and plants in the Dead Sea, in such brine only bacteria live.

Of the recognized seas, the Red Sea is considered the most salty. 1 liter of water contains 41 g of salt.

In Russia, the most salty sea is the Barents Sea (34-37g/l).

The biggest sea

(Philippine Sea)

The largest sea in the world is the Philippine (5726 thousand sq. km). It is located in the western part of the Pacific Ocean between the Taiwan, Japanese and Philippine islands. This sea is also the deepest in the world. The greatest depth was recorded in the Mariana Trench - 11022 m. The territory of the sea immediately covers 4 climatic zones: from equatorial to subtropical.

The largest sea in Russia is Beringovo (2315 thousand sq. Km.)

It is divided into separate parts (Fig. 1).

Rice. 1. Parts of the oceans

First of all, the World Ocean is a collection of individual oceans (Table 1).

Table 1. Main characteristics of the oceans (according to K.S. Lazarevich, 2005)

	Total area, mln km2	Average depth, m	Maximum depth, m	Volume, mln km3
			11,022 (Marian Trench)
Atlantic			8742 (Puerto Rico Trench)
Indian			7729 (Zonda Trench)
Arctic			5527 (Greenland Sea)
World Ocean			11,022 (Marian Trench)

The basis for this division is the following:

• configuration of the coastline of the continents, archipelagos and islands;
• bottom topography;
• independent systems of ocean currents and atmospheric circulation;
• characteristic features of the horizontal and vertical distribution of the physical and chemical properties of water.

The boundaries of the oceans are extremely arbitrary. They are carried out along the continents, islands, and in the expanses of water - along underwater elevations or conditionally along meridians and parallels.

The smaller and relatively enclosed parts of the oceans are known as seas, bays, and straits.

Sea classification

Sea- a part of the ocean, as a rule, isolated by islands, peninsulas and above-water heights. The exception is the so-called sea without shores - the Sargasso Sea.

Seas make up 10% of the world's oceans. The Philippine Sea is the largest sea on Earth. Its area is 5726 thousand km 2.

The seas differ from the open part of the ocean in a special hydrological regime and other natural features, which is due to some isolation, a large influence of land and slow water exchange.

The seas are classified according to different criteria. By location seas are divided into:

• marginal, which are located on the underwater continuation of the continents and are limited from the side of the oceans by islands and underwater heights (for example, the Barents Sea, the Bering Sea, the Tasman Sea; they are all closely connected with the ocean);
• internal (Mediterranean), which flow far into the land, connecting with the oceans through narrow straits, often with uplifts of the bottom - underwater rapids, differing sharply from them in hydrological regime. Inland seas, in turn, are subdivided into inland(for example, Baltic and Black) and intercontinental(for example, Mediterranean and Red);
• interisland, more or less surrounded by a dense ring of islands and underwater rapids. These include the Javanese, Philippine and other seas, the regime of which is determined by the degree of water exchange with the ocean.

By the origin of the basins seas are divided into:

• continental (epicontinental), which are located on the shelf and arose due to the increase in water in the ocean after the melting of glaciers when ocean water came to land. This type includes most of the marginal and many inland seas, the depths of which are relatively small;
• oceanic (geosynclinal), which are formed as a result of cracks and faults earth's crust and sinking land. Basically, they include intercontinental seas, the depths of which increase towards the center up to 2000-3000 m and have basins that are relatively symmetrical in shape. They are characterized by tectonic activity, and usually they cut through the continental base. All interisland seas are also located in the zones of tectonic activity of the Earth, and the islands surrounding them serve as the peaks of seamounts, often volcanoes.

The border between land and sea, the so-called coastline, as a rule, very uneven, with bends in the form of bays, peninsulas. Along the coastline, islands are usually located, separated from the mainland and from each other by straits.

Bay classification

gulf The part of the ocean that extends deep into the land. Bays are less isolated from the oceans and are classified into different types:

• fjords - narrow, long, deep bays with steep banks, protruding into mountainous land and formed at the site of tectonic faults (for example, Sognefjord);
• estuaries - small bays formed on the site of river mouths flooded by the sea (for example, the Dnieper Estuary);
• lagoons - bays along the coast, separated from the sea by spits (for example, the Curonian Lagoon).

There is a division of bays according to sizes. The largest bay on Earth, both in area and in depth, is the Bay of Bengal. Its area is 2191 thousand km 2, and the maximum depth is 4519 m.

Essentially similar water areas can be called in some cases bays, and in others - seas. For example, the Bay of Bengal, but the Arabian Sea, the Persian Gulf, but the Red Sea, etc. The fact is that their names have existed since historical times, when there were not enough clear definitions and ideas about water bodies.

Strait classification

strait A relatively narrow part of an ocean or sea that separates two land areas and connects two adjacent bodies of water.

By morphology Straits are divided as follows:

• narrow and wide straits (the widest Drake Passage is 1120 km);
• short and long straits (the longest one is Mozambique - 1760 km);
• shallow and deep straits (the deepest Drake Passage is 5249 km).

According to the direction of water movement, there are:

• flowing straits, in which the current is directed in one direction (for example, the Florida Strait with the Florida Current);
• exchange straits, in which the currents pass in opposite directions along different coasts (for example, in the Davis Strait, the warm West Greenland Current is directed north, and the cold Labrador Current is directed south). In opposite directions on two different levels currents pass in the Bosporus Strait (the surface current from the Black Sea to the Sea of ​​Marmara, and the deep one - vice versa).

Of the total area of ​​the planet, equal to 510 million km 2, 361 million km 2 is occupied by the waters of the oceans, which is about 71% of the entire surface area of ​​the Earth. This predominance of water determines many key features Earth as planets - climate, life forms, the nature of the exchange of energy and matter between individual geospheres, etc. The World Ocean contains 96.4% of the total amount of water on Earth (including continental ice Antarctica and Greenland - see Ch. 3), so its water can be considered as an independent shell - oceanosphere. Despite the predominance of the water surface, total water compared to the size of the planet itself is small and is approximately 1/800 of the volume of the Earth. Consequently, on a planetary scale, the World Ocean is a relatively thin film on the surface of the Earth.

In accordance with the configuration of the coasts, the topography of the bottom, the dynamics of water and atmospheric circulation, the nature of the distribution of hydrological characteristics (temperature, salinity), the World Ocean is divided into separate oceans. Ocean- a vast part of the World Ocean, located between the continents, having an independent system of water circulation and specific features of the hydrological regime. In the process of evolution of our knowledge about the oceans, various options for dividing the World Ocean appeared. It is generally accepted to distinguish four oceans: the Atlantic, Pacific, Indian and Arctic. Their morphometric characteristics are given in table. 10.1.

As can be seen from the table, the area of ​​the Pacific Ocean is almost half of the entire area of ​​the World Ocean and exceeds the surface of all the continents and islands of the Earth. The Pacific Ocean has the greatest average depth, and the deepest Mariana Trench in the World Ocean is also located here. Its maximum depth is 11,022 m; it was measured by an expedition aboard the Soviet research vessel Vityaz in 1957.

Table 10.1.Main morphometric characteristics of the oceans*

In my own way geographic location, morphometric characteristics and features natural conditions The Arctic Ocean differs significantly from other oceans. Its area is 12 times less area Pacific Ocean, 6 times - Atlantic and 5 times - Indian. The average depth of the Arctic Ocean is about three times less than that of other oceans. The ratio of the area of ​​this ocean to the area of ​​its drainage basin is 0.92, while for the Pacific Ocean this ratio is 0.04, for the Atlantic - 0.3, for the Indian - 0.09.

AT recent times a fifth ocean is also often distinguished - the Southern Ocean, which, in accordance with the definition of the ocean given above, is indeed an independent object with a specific regime. In the south, it extends to the coast of Antarctica, but in the north it does not have a clearly defined border: it is drawn either along the northern border of the Antarctic Circumpolar Current, or along a line connecting the southern extremities of South America, Africa, Tasmania and New Zealand. The total area of ​​the Southern Ocean is about 80 million km2. This means that the southern sectors of the three most major oceans, and it will be the second largest after the Pacific.

Seas are distinguished within the oceans. Sea- a relatively small part of the ocean that protrudes into the land or is isolated from its other parts by the coast of the mainland, bottom elevations (thresholds) or islands and has specific features of the hydrological regime. The area of ​​the seas is about 10% of the total area of ​​the World Ocean, and the volume of water in the seas does not exceed 3% of the volume of the waters of the World Ocean. According to the degree of isolation and location relative to land, the seas are divided into internal (Mediterranean), marginal and interisland.

inland seas they usually go deep into the land and have a difficult connection with the ocean through relatively narrow straits. In turn, inland seas are divided into intercontinental (for example, the Mediterranean, Red) and inland (located within the same continent, for example, the Baltic, White, Black, Azov). The hydrological regime of these seas usually differs significantly from that of the adjacent part of the ocean.

marginal seas relatively shallowly protrude into the land and are separated from the ocean by peninsulas, ridges of islands or rapids (for example, the Barents, Kara, Okhotsk, and Japanese seas). The water exchange of these seas with the ocean is greater than that of the internal ones, and the hydrological regime is closer to that of the adjacent part of the ocean.

borders interisland seas are islands and uplifts of the bottom (for example, the Banda, Fiji, Philippine seas).

Total number There are about 60 seas in the World Ocean according to the division adopted by the Intergovernmental Oceanographic Commission of UNESCO. The characteristics of the main seas are given in Table. 10.2. At the same time, a number of seas are distinguished only by states that border them. For example, the Tyrrhenian and Ionian seas are often distinguished inside the Mediterranean Sea, the Pechora Sea is distinguished in the eastern part of the Barents Sea, etc. The largest sea in the World Ocean and at the same time the deepest is the Philippine (5.7 million km 2), the trough of the same name has a depth of up to 10,265 m. The volume of this sea is 30% larger than the volume of the entire Arctic Ocean. The largest sea area in pacific ocean, in addition to the Philippine - Coral (4.1 million km 2), South China (3.5 million km 2), Tasmanovo (3.3 million km 2), in the Atlantic Ocean - Weddell (2.9 million km 2) , Caribbean (2.8 million km 2) and Mediterranean (2.5 million km 2), in Indian - Arabian (4.8 million km 2), and in the Arctic - Barents (1.4 million km 2) and Norwegian (1.3 million km 2).

In the oceans and seas, separate parts are also distinguished, differing in the configuration of the coasts, bottom topography and hydrological regime. First of all, these are straits and bays.

strait- a body of water that separates two land areas and connects separate oceans and seas or parts of them. An example is the Bering Strait, which connects the Pacific and Arctic oceans (and separates Asia and North America), Gibraltar, connecting the Mediterranean Sea with the Atlantic Ocean (and dividing Europe and Africa), La Perouse between the islands of Sakhalin and Hokkaido, connecting the Sea of ​​Okhotsk and the Sea of ​​Japan. The width of the strait is the distance between the land areas separated by water, the length of the strait is the distance between the main water bodies (between the inlet and outlet sections). The widest is the Drake Passage separating South America and Antarctica (about 1000 km), and the longest strait is Mozambique (almost 1800 km). Straits are very diverse, they play a very important role in the formation of the hydrological regime in the water bodies they connect, and in themselves represent an important object of study.

Table 10.2.Main morphometric characteristics of some seas of the world*

* Atlases of the oceans. Terms. Concepts. Reference tables. GUNIO MO USSR, 1980.

Bay - part of the ocean or sea that protrudes into the land and is not separated from it by islands or bottom uplifts. As a result, the regime of the bay differs little from the adjacent region of the ocean or sea. Examples include the Bays of Biscay and Guinea in the Atlantic Ocean, California in the Pacific Ocean, Bengal (the largest in area - 2.2 million km 2) and the Great Australian in the Indian Ocean.

It should be borne in mind that the allocation of individual seas and bays, as well as their boundaries, is a historical tradition, sometimes leading to contradictions. A number of regions of the World Ocean, which have the same isolation and peculiar features of hydrological conditions, are called seas in some cases, and bays in others. For example, such ocean bays as the Mexican, Persian, Hudson, it would be more correct to call the seas, the Arabian and Beaufort seas are more like bays, and the Sargasso Sea, which does not have shores, is essentially inner part subtropical gyre of the North Atlantic.

Depending on the origin, shape, structure of the shores, the bays have different, often local names: a bay, an estuary, a fiord, a bay, a lagoon, etc.

Bay- a small bay, separated by capes or islands from the main body of water (i.e., the ocean or sea), usually well protected from the winds and often used for ports. Each bay has a special hydrological regime. Examples of such water bodies are the Sevastopol and Tsemesskaya bays on the Black Sea, the Golden Horn and Nakhodka in the Sea of ​​Japan.

Estuary - a bay separated from the sea by a sandy spit (bay), in which there is a narrow strait connecting the estuary with the sea. Usually, an estuary is a flooded part of the section of the river valley closest to the sea (for example, the Dnieper-Bugsky, Dniester estuaries on the Black Sea coast). The characteristics of the waters in the estuary can be strongly influenced by the river flowing into it. These bodies of water are sometimes referred to as lakes, but it is more correct to consider them as parts of the mouth areas of rivers (see Section 6.14).

Lip- common in the north of Russia, the name of the bay, deeply protruding into the land, as well as the vast bay into which the river flows (Cheshskaya in the Barents Sea, Obskaya in the Kara Sea). It is also expedient to attribute these water areas to the estuarine areas of the rivers.

A narrow and deep sea bay with high shores (usually the bed of an ancient glacier) is called fiord(for example, Sognefjord in the Norwegian Sea).