Once a year, crowds of tourists flock to the South Korean archipelago of Jindo: due to the increasing tides between its two islands, waves recede into the sea - and a land road opens almost three kilometers long and forty meters wide, which is an analogue of the famous miracle of Moses described in the Old Testament . Tourists use this opportunity to walk along the exposed bottom, take pictures and collect shells.

Since the seas appeared on our planet relatively recently, from 20 to 2 million years ago, they are considered young geological formations. The deepest reservoirs arose in places where, as a result of the displacement of lithospheric plates, large faults formed in the earth's crust. For example, the deepest sea in the world, the Philippine, is considered so because of the trough located at its bottom, the depth of which exceeds 10.5 km, when the average depth of the sea reservoir is about 4 km.

A sea is a part of the World Ocean, separated from it by land areas or elevations of underwater relief, always having water communication with it, which are straits or bays. If the seas and oceans do not connect with each other in any way, then such a body of water is considered a lake, for example, the Caspian or Dead Sea.

Due to the fact that almost all sea water bodies are located near the coast of the continent or are located inside the mainland, and the speed of sea currents is low due to limited connection with the World Ocean, they differ from it in salinity, depth, water structure, climate, relief, flora and fauna (the farther from the ocean, the more noticeable the difference).

Marine reservoirs can be part of another sea - in this case they are distinguished depending on the flora and fauna: endemics are often found among the inhabitants of the deep sea, which can be seen in the example of the Aegean, located on the outskirts of the Mediterranean Sea.

Salinity

An important characteristic of a sea body of water is its salinity, which they receive thanks to rivers that take out dissolved salts from the depths of our planet and carry them to the seas. True, the level of their salinity differs significantly from each other. Thus, reservoirs with a high salt content (for example, the Red Sea is considered the most salty sea in the world) have more high level salinity than in the ocean: due to active evaporation, part of the water goes into the atmosphere, and salt goes to the bottom, where it gradually accumulates.

But the slightly saline seas have a lower level of salinity than in the World Ocean, because due to climatic conditions, water evaporates slowly, which makes it possible for it to escape through the straits (the Baltic is the freshest sea in the world).

Temperature

Up to a depth of two hundred meters, the sea temperature depends on the geographical latitude and season: in areas with a hot climate, the water temperature will be from + 25 to + 30 ° С, in polar latitudes it can drop to -1.8 ° С (it does not freeze only due to dissolved salts in sea water).

But at great depths, currents affect water temperature indicators, the deeper they are, the colder the water (Philippines, the deepest sea in the world, at its lowest point has a temperature of about zero degrees).

As for the coldest sea body of water in the world, it is considered to be the East Siberian Sea, which is part of the Arctic Ocean: it is almost always covered with ice, and the water temperature in its northern part practically does not change throughout the year and is -1.8 ° C, and in the south in the summer the sea can warm up to five degrees above zero.

Tourists are recommended to relax on the Red Sea coast. It is located between the Arabian Peninsula and Africa and is the warmest sea body of water in the world. In summer the water temperature is +27°С, in winter it does not fall below +20°С.

Sea waves

Despite the fact that sea reservoirs are characterized by rather weak currents, the water in them moves even when the surface of the sea seems perfectly flat in clear weather. But the waves of the sea still beat against the shore - quietly, weakly, barely noticeable, but constantly advancing on the coast and retreating. They appear due to the wind, and their size depends on the strength of the air flow that comes into contact with the water and, through friction, creates pressure on the crests of the waves (the shallower the depth, the smaller the waves). If there is no wind at all, then there is a swell and imperceptibly advancing waves on the coast.

Also characteristic waves are seiches - standing waves that rise and fall in the same place. This phenomenon lasts from several minutes to tens of hours. Despite the fact that the average wave height is thirty centimeters, it may well vary from a few millimeters to five meters (it all depends on the relief of the coast and the depth of the reservoir). Seiches are not as harmless as it seems at first glance, and are primarily dangerous for small ships, boats and even people on the coast: unexpectedly rising high waves may well “drag” a person under water.

Sea classification

Interestingly, scientists have not yet been able to come to a consensus on how many seas exist on our planet, since there are bodies of water that are difficult to classify and attribute to a sea, lake or bay. Therefore, the official definition is questionable - and everyone puts them in the category that suits him the most.

According to the International Hydrological Organization, there are sixty-three seas on Earth. Some scientists question these data, pointing out that many small marine reservoirs that are part of larger ones are not taken into account here, and therefore there are much more reservoirs of this type and their number is close to a hundred.

To convince opponents, a map of the seas is given as an example (it should be noted that in this list, many bays also fell into the category of seas, for example, Persian, Bengal, Mexican).

According to these data, there are about thirty seas in the Pacific Ocean, thirteen in the South, eleven in the Arctic, and six in the Indian. The number of marine reservoirs of the Atlantic Ocean causes the greatest disagreement among scientists and their number ranges from sixteen to thirty.

One of the most popular classifications is the division of the seas according to the degree of their isolation from the ocean:

• Internal - located at a great distance from the ocean, have limited water exchange with it and are connected by one or more straits;
• Marginal - located off the coast of the ocean, are part of it and are located on the shelf;
• Interisland - are part of the World Ocean and are separated from it by a ring of islands, inside which the elevation of the relief slows down the water exchange of these seas with the ocean. An island in the sea or in the ocean is usually the top of a high seamount or appears as a result of seismic activity (earthquakes, volcanic eruptions). Sometimes it is artificially created by people when they form an artificial island in the sea for their own needs (for example, during the construction of the Burj Al Arab hotel in the UAE).

Starting point

As a result of many years of observations several centuries ago, scientists came to the conclusion that it is the level of the sea surface that is the ideal starting point from which it is possible to measure the height of objects both above and below it. Therefore, it was decided to consider it absolute altitude, the zero reference point (in contrast to it, the relative height shows how much higher or lower one point is in relation to another).

It should be noted that the height above sea level is a rather arbitrary concept, since our planet is not quite round in shape and is slightly flattened at the poles. Due to the different salinity levels of the Atlantic and Pacific oceans and the constantly changing direction of air currents, the height difference from the surface of the two oceans is about 20 cm.

For example, in Russia, the zero point is the mark of the Kronstadt footstock (level gauge, which is a rail with divisions), which was installed in Kronstadt on the coast of the Baltic Sea.

But the depth and height in Western Europe are calculated using a level gauge installed in Amsterdam, the level of the Mediterranean Sea is calculated using a rail installed on the coast of Marseille. Other continents also have their own reference level.

Sea vessels in human life

The sea significantly influenced the development of civilization: as soon as a person built his first ship, he began to surf the sea in search of ways to new lands, make great geographical discoveries, discovering one or another continent or island in the sea, develop trade, science, art.

It's not surprising that Special attention he paid attention to the development of maritime transport: throughout the history of mankind, ships have played an important role in the life of society. And even now, despite the huge number of alternative modes of transport, more than 60% of the world's transport cargo turnover falls on ships.

Transportation of cargo by ships is 40% cheaper (this is especially beneficial for small countries whose borders are by sea) than transporting by rail. Recently, with the development of technology, ships began to move at a fairly decent speed, and some of them are able to accelerate to 100 km / h).

In addition, the depths of the sea are fraught with a huge amount of natural wealth (for example, oil), which a person has learned to extract and use. Since almost all oil fields are located in the sea, and some are many kilometers from the coast, it was with the help of ships that people were able to get to the minerals.

Thanks to ships, a person got the opportunity to develop fishing: about 90% of the catch is caught in the seas and oceans (most fish are caught in the northern hemisphere). Unfortunately, for many fishermen, fishing is a real hunt, and therefore it is often carried out uncontrollably, which leads to the disappearance of many rare species of marine life. There is hope that this process will be brought under control and poaching will be replaced by rational forms of fishing.

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. Such a predominance of water determines many of the most important features of the Earth as a planet - climate, life forms, the nature of the exchange of energy and matter between individual geospheres, etc. The oceans contain 96.4% of the total amount of water on Earth (including the continental ice of Antarctica and Greenland - see . ch. 3), so its waters can be considered as an independent shell - oceanosphere. Despite the predominance of the water surface, the total amount of 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*

According to its geographical location, morphometric characteristics and features natural conditions The Arctic Ocean differs significantly from other oceans. Its area is 12 times smaller than the area of ​​the Pacific Ocean, 6 times smaller than the Atlantic Ocean, and 5 times smaller than the Indian Ocean. 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.

Recently, a fifth ocean has often been distinguished - the Southern Ocean, which, in accordance with the above definition of an ocean, 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. total area The Southern Ocean is about 80 million km2. This means that the southern sectors of the three largest oceans will go to the Southern Ocean, 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).

The total number of seas in the World Ocean according to the division adopted by the Intergovernmental Oceanographic Commission of UNESCO is about 60. 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 seas in the Pacific Ocean, in addition to the Philippine, are 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 the 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, connecting the Pacific and Arctic Oceans (and separating 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, having the same isolation and peculiar features of hydrological conditions, are called seas in some cases, and bays in others. For example, such oceanic gulfs as the Mexican, Persian, Hudson, it would be more correct to call the seas, the Arabian and Beaufort seas are more like gulfs, and the Sargasso Sea, which does not have shores, is essentially the inner part of the subtropical circulation 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).

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 breaks and faults of the earth's crust and the sinking of 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). Currents in the Bosporus pass in opposite directions at two different levels (the surface current from the Black Sea to the Sea of ​​Marmara, and the deep one, vice versa).

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 were formed at the break of tectonic plates, for example, 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 creating the temperature regime of the globe. Sea water is 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. At the same time, salt water begins to freeze at a temperature of -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.

An interesting feature of the water in the sea is known. 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, only bacteria live in such a saline solution.

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 covers 4 climatic zones at once: from equatorial to subtropical.

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

Today there are 81 seas.

All seas are divided according to their location according to following directions: Atlantic, Pacific, inland seas and seas, with the Southern Ocean, the 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 are even seas of garbage, which, due to the large amount of waste, turn 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 the ecological situation and the issue of the preservation of water resources is becoming more acute every year: scientists suggest that climate change and the active expansion of man into the natural elements will wipe more than one sea from the face of the planet, and war between peoples is not far off, not for territory, but for fresh and salt water.