What you should know about the Baltic Sea

Baltic – our sea

It is young, shallow, not too big, cold and not too salty. Its name comes from the Old Slavic word blato, meaning great, salty water. It has its holiday on March 22 – Baltic Sea Protection Day.

The Baltic Sea is quite small

Some even claim that it is a large lake. Its area is about 415 thousand square kilometers, the volume of about 22 thousand cubic kilometers, the length of the developed coastline is about 22 thousand kilometers. Because it is surrounded by land on all sides, it is sometimes called the Mediterranean Sea of northern Europe. The Baltic exchanges water only with the North Sea – through the narrow and shallow Danish Straits: Great and Little Belt, Sound, Skagerrak, Kattegat. The total exchange of water in the central Baltic Sea lasts from 25 to 30 years.

The Baltic Sea extends widely from north to south for almost 1,300 km, while from east to west it is more than half as long - measuring about 600 km. The narrowest part of the Baltic - the Gulf of Bothnia - is about 100 km long.

The Baltic Sea has a varied coastline

It consists of: islands, such as Funen, Bornholm, Usedom, Rugen, Wolin and Gotland; straits, such as the Great and Small Belt, Øresund; peninsulas, such as Hel, Skåne; spits, such as the Curonian, Vistula; bays, such as Bothnian, Finnish, Pomeranian, Gdansk, Riga; lagoons, such as the Vistula, Szczecin, Curonian. The Baltic Sea has both low coasts, e.g. in Finland, Latvia or Russia, spits (Vistula Spit), and high coasts: skerries (numerous small, rocky islands) in Finland, fjord-skerries in Norway, Sweden, Finland, cliffs when the sea destroys the high shore – in Poland (Wolin, Gdynia, Jastrzębia Góra), Denmark, Estonia and fjords in Denmark.

The Baltic Sea is Europe's youngest sea

Its history is connected with the period of the last glaciation and dates back to 12 thousand years ago. The range and character of the Baltic Sea changed depending on climatic changes and isostatic movements. Interestingly, the Baltic was twice a lake in the past! Major phases of development: Baltic Ice Lake, Yoldi Sea, Ancylus Lake, Litorin Sea and contemporary – Mya Sea.

The Baltic Sea is shallow

Its average depth is only 52.3 m, the maximum 459 m (Landsort Depth). For comparison: the average depth of the Caspian Sea is 184 m, the Red Sea – 490 m, the Mediterranean Sea – 1438 m.

The Baltic Sea is cold!

Located in the north temperate zone, it is not heated by the warm Gulf Stream. The average temperature of the Baltic Sea ranges from 12 to 17 degrees Celsius in summer and from 2 to 4 degrees Celsius in winter. During cold winters, the surface waters are partially iced (e.g. in the Gulf of Bothnia and the Gulf of Finland).

The Baltic Sea is the least saline sea in the world, therefore it is said to be a brackish sea.

In a liter of the Baltic Sea water there is on average 7 g of salt; in the middle of the Baltic Sea the salinity does not exceed 10 g of salt per liter, while the closest to the North Sea – in the Danish Straits – it ranges from 20 to 30 g. The average for the world's seas is 35 g of salt per liter of water. There is also a lot of freshwater in the Baltic Sea, which is due in part to the large influx of freshwater from the surrounding area. A total of about 250 rivers flow into the Baltic Sea, the largest of which are: Vistula, Oder, Neva, Kemi and Neman.
The low salinity affects the animals that live in our sea. Baltic fish and invertebrates are up to half the size of the same species in the North Sea!

The transparency of the Baltic Sea varies depending on the season.

Historically recorded: 6-15 m in the Gulf of Gdansk, up to 19 m near Bornholm. In 2015, the average annual transparency was from 3.83 m in the Gdansk Basin to 9.75 m in the Bornholm Basin.  For comparison: the transparency of the White Sea is 10 m, the Black Sea 25 m. In the cleanest part of the Mediterranean Sea (area of Cyprus and Israel) the transparency reaches 53 m. 

Variable, stormy and green

From blue during beautiful sunny weather to steel gray during stormy weather. The Baltic Sea takes on a different hue almost every day, depending on the amount of sunshine, the angle of the sun, how cloudy it is, how salty the water is, and how deep it is. Although it takes on different colors, it is classified as a green sea because its waters are full of all kinds of suspended solids, which include, among others, small organisms. The green color is also associated with low water temperature and low salinity.

The Baltic is a stormy sea,storms occur frequently, seiches (vertical standing waves) appear. On average, storm waves are quite short and steep, usually 5 m high. However, during exceptionally strong storms, they can reach heights of up to 10 m.

Fauna and flora of the Baltic Sea

Microscopic living organisms that float on the surface of water. Common: diatoms, cyanobacteria, dinoflagellates.

Seabed plants. These include kelp (forkbeard, curette), flowering plants (seagrass), brown algae (seaweed), and green algae (sea lettuce).

Living organisms,  unicellular or multicellular, e.g.: rotifers, rotifers, crustaceans, copepods, protozoa, crustacean and fish larvae.

Animals that live on the sea floor. These include: poriferans (bread clover), bivalves (mussels, cockles), crustaceans (shrimp, gudgeons), and snails (waterfleas).

Marine mammals and fish. Mammals include: porpoises, gray seals, common seals, ringed seals. Saltwater fish: herring, sprats, cod; freshwater fish: perch, pikeperch, smelt; and bi-environmental fish: eels, salmon, sea trout.

Fauna i flora Morza Bałtyckiego

Mikroskopijne organizmy żywe, unoszące się na powierzchni wody. Często spotykane: okrzemki, sinice, bruzdnice.

Rośliny dna morskiego. Są to: krasnorosty (widłak, rurecznica), rośliny kwiatowe (trawa morska), brunatnice (morszczyn), zielenice (sałata morska).

Organizmy żywe,  jednokomórkowe lub wielokomórkowe, np.: wrotki, wioślarki, skorupiaki, widłonogi, pierwotniaki, larwy skorupiaków i ryb.

Zwierzęta żyjące na dnie morskim. Zaliczamy do nich: gąbki (powłócznica chlebowa), małże (omułek, sercówka), skorupiaki (krewetki, kiełże), ślimaki (wodożytka).

Ssaki morskie i ryby. Ssaki to: morświny, foki szare, foki pospolite, foki obrączkowane. Ryby słonowodne: śledzie, szproty, dorsze; ryby słodkowodne: okonie, sandacze, stynki oraz dwuśrodowiskowe: węgorze, łososie, trocie wędrowne.

National parks and Baltic beaches

There are two national parks by the Baltic Sea: Slowinski and Wolinski. Both were established in the sixties of the last century.

Słowinski National Park pis located in the central part of our coast. On its territory there are lakes, peat bogs, as well as dunes. Wandering dunes are an attraction. About 920 species of vascular plants, about 165 species of bryophytes, about 500 species of algae and about 430 species of fungi live in the park. There are also more than 260 bird species and more than half of all mammal species found in Poland.

Wolinski National Park is located in the central-western part of the island of Wolin. About 600 species of vascular plants live here, many of which are very rare. The island is a nesting place for many birds. Migratory birds also pass through the park. An attraction of Wolinski National Park are steep cliffs.

On the entire southern coast of the Baltic Sea, including Poland, we have beautiful sandy beaches. This is unique, because only less than 30 percent of beaches in the world are sandy beaches.

Hel Peninsula

Only 35 km long, at the narrowest point less than 100 m, at the widest about 3 km. There are so narrow places on the Hel Peninsula that driving down the road, on one side you see the open sea, and on the other – the waters of the bay.

The peninsula was formed by the activity of sea currents and waves and wind. The west wind blowing along the coast caused the formation of a current flowing from west to east. Together with the masses of water also flowed material from the erosion of coastal cliffs. Beyond Rozewie, the current changed its direction to the south, resulting in the formation of a sandbank.

Hel was not always drivable along its entire length. At the end of the 16th and 17th centuries it consisted of six islets. They were formed periodically, during the biggest storms

Gold of the Baltic

There is no Baltic Sea without amber! Even the stadium in Gdańsk, built for Euro 2012, refers to amber. The Polish name of amber (bursztyn) comes from the German word Bernstein, and this from the Old High German – börnen, meaning to burn. In Russian amber is called yantar and in French – succin.

Amber is the mineralized resin of coniferous trees that has been dripping from the trees for thousands of years. When the land was under water, the resin deposits were mixed with the ground. Amber has many colors, from yellowish-white through brownish-red to the color of honey. The most sought after are those lumps in which various creatures have frozen – flies and mosquitoes, termites, butterflies, cicadas, centipedes, and spiders.

The largest amber found so far, called Burma Amber, weighs 15.25 kg. This specimen is in the British Museum in London. The largest Baltic amber found near Kamień Pomorski weighed 9.75 kg..


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