The environmental status of the Baltic Sea is a shared concern for all countries surrounding it. Consequently, the Baltic Sea region has become one of the most active areas for international co-operation in environmental protection. Countries need to work together to identify the best solution for managing the sea and coastal areas in a manner that both fosters national prosperity and job creation and safeguards the marine environment.
Managing the protection of the Baltic Sea
The Baltic Sea States co-operate in regulating and organising the protection of the Baltic Sea. The basis for co-operation is the Convention on the Protection of the Marine Environment of the Baltic Sea Area joined by Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden and the Community. The Convention was first introduced in 1974 and re-introduced in 1992, when Estonia also joined.
To implement the goals of the Convention, an intergovernmental committee, the Baltic Marine Environment Protection Commission (HELCOM), was formed. The work of the committee is organised by Baltic Sea States, whereas the presidency rotates every two years according to alphabetical order. The country of location of the committee is Finland (Helsinki) and the permanent Secretariat is comprised of experts and the Secretary General.
The following working groups have been formed: HELCOM MONAS, HELCOM LAND, HELCOM HABITAT, HELCOM MARITIME and HELCOM RESPONSE, HELCOM GEAR. The work of the Estonian delegation in HELCOM working groups. The work is organised and coordinated by the Marine Environment Department of the Ministry of the Environment.
More information on the cooperation for the protection of the Baltic Sea: http://www.helcom.fi
What is the Baltic Sea?
- Area: The total area of the Baltic Sea is 415,266 km2, whilst the basin – 1.7 million km2 – is four times the size of the sea itself.
- Depth: the average depth of the Baltic Sea is approximately 50 metres. The greatest deep is the off-shore Baltic Sea Landsort Deep with an estimated depth of 459 metres. The charge of water in the Baltic Sea is approximately 21,000 km3. The water turnover in the Baltic Sea is approximately 2% per year, meaning that the total water turnover takes about 25 years.
- Basin: In Germany, Denmark and Poland 60–70% of the Baltic Sea basin is comprised of cropland. In Finland, Russia, Sweden and Estonia 65–90% of the Baltic Sea basic is comprised of forests, wetlands and lakes.
- Population and countries: Almost 85 million people live in the basin of the Baltic Sea, of whom 26% live in large capital areas, 45% in smaller urban areas and 29% in rural areas. The population density is between 500 habitats per square kilometre in the urbanised areas of Poland, Germany and Denmark and under 10 habitats per square kilometre in the northern regions of Finland and Sweden. Almost 15 million people live within ten kilometres from the coast.
- Countries that lie on the Baltic Sea are: Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Sweden and Russia. Countries lying on the basin of the Baltic Sea are Ukraine, Czech Republic, Belarus and Slovakia. The largest islands in the Baltic Sea are Saaremaa, Hiiumaa, Gotland, Bornholm, Rügen and the Åland Islands.
- Shipping: Every year over 500 million tons of cargo is shipped on the Baltic Sea through numerous and widely used sea lanes. Over 50 passenger ferries operate between the harbours of the Baltic Sea.
The Baltic Sea is connected to the ocean only through the narrow and shallow Strait of Øresund (the Sound) and the Belts (the Great Belt and the Little Belt), limiting the exchange of water with the North Sea. As a result, the same water, along with all the organic and inorganic matter it contains, remains in the Baltic Sea for up to 30 years.
The Baltic Sea is made up of a number of sub-basins, mostly separated by shallow sills. Each of these basins has its own water exchange characteristics. The catchment area of the Baltic Sea is nearly four times larger than the sea itself. The Baltic Sea has a water volume of 21,547 km3, and each year, rivers discharge nearly 2% of this volume into the sea as runoff.
Brackish water is the water of a natural body of water with a salinity ranging between 0.5 and 18. Brackish water bodies are home to euryhaline marine and freshwater organisms as well as specific brackish water organisms. The brackish water of the Baltic Sea is a mixture of North Sea water and freshwater from rivers and precipitation. The salinity of the sea surface water ranges from approximately 20 in the Kattegat to 1–2 in the northernmost Gulf of Bothnia and the easternmost Gulf of Finland. For comparison, the salinity in the open ocean typically averages around 35.
Salinity levels vary with sea depth, increasing towards the seabed. The saltier water entering through Strait of Øresund (the Sound) and the Belts (the Great Belt and the Little Belt) does not mix easily with the less dense Baltic Sea water and instead sinks to deeper basins. At the same time, less salty surface water flows out of the Baltic Sea. The transition zone between these two water masses, known as the halocline, consists of a layer where salinity changes rapidly. For example, in the open Baltic Sea and the Gulf of Finland, the halocline is located at a depth of about 60–80 metres. The halocline acts as a barrier, limiting vertical mixing of the water.
The open Baltic Sea is primarily replenished by the oxygen-rich saltwater flowing in from the North Sea along the seabed. In the Gulf of Bothnia, the halocline is either very weak or absent. In the summer, the thermocline – a distinct layer where temperature changes rapidly – divides the surface water into two layers: a mixed surface layer, which extends to a depth of 10–25 metres, and a deeper, denser and cooler layer that reaches the seabed or halocline.
Compared to other aquatic ecosystems, the Baltic Sea ecosystems host relatively few animal and plant species. This limited biodiversity is composed of a unique mix of marine and freshwater species adapted to brackish water conditions, along with a few true brackish water species.
In the northern and eastern parts of the Baltic Sea, where salinity is low, fewer marine species can thrive and freshwater species dominate the marine habitats, particularly in estuaries and coastal waters.
The length of the coastline of the Estonian maritime area (according to the base map, including islands and islets) is approximately 4,015 km. The total area of the Estonian maritime area is approximately 36,622 km2, with the exclusive economic zone making up nearly one third of this, covering approximately 11,420 km2. Estonia is home to 1,521 sea islands, of which only 318 are larger than one hectare (10,000 square metres).
Last updated: 30.07.2025
