The Northern Bothnian Bay

Two countries and one common sea. The marine environment of the northern Bothnian Bay is a shared resource and responsibility for Sweden and Finland, but little is known about it. Within the SEAmBOTH project we are trying to change this.

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The calm surface of the sea in the National Park of Bothnian Bay (Photo by Niina Kurikka, Metsähallitus).

The Bothnian Bay is the northernmost bay of  the Baltic Sea, and it is quite different from the rest of it. The area has the lowest salinity in the Baltic Sea, almost ten times lower than in the south. If you swim in the waters around Haparanda/Torneå you will see that it is very brown. The brown water is caused by the large outflow of water from nearby rivers.  Due to the low salinity and brown waters, a unique mix of freshwater and marine species can be found here.

Vegetation below the surface in the Bothnian Bay, Haparanda, Sweden (Photo by Aimi Hamberg, County Administrative Board of Norrbotten).

Because of the uniqueness of our marine area, many standard methods for inventory work and mapping developed nationally in our respective countries are not readily applicable to the northern Bothnian Bay. Also, manuals and national guidelines for management or definitions e.g. nature type definitions, seldom have accounted for the special conditions of the Bothnian Bay. As a result, the knowledge of  life below the surface and the condition of the bottom in the Bothnian Bay is exceptionally scarce.


Both Finland and Sweden have committed themselves to protecting biological diversity and ecosystem services through the Convention of Biological Diversity (CBD) and the Helsinki Commission (HELCOM). In addition, Finland and Sweden have EU legislation to follow, namely the Marine Strategy Framework Directive, the Water Framework Directive, the Habitats Directive and the Maritime Spatial Planning Directive. Increasing the knowledge of the marine environment of the Bothnian Bay is therefore crucial for both countries to be able to fulfill national and international commitments.

How do the SEAmBOTH project contribute to care for the marine environment in the Bothnian Bay then? By for example ensuring managers have the essential knowledge, i.e. in the form of maps showing areas with high nature values, it may help them in planning where and how human activities can take place and where they should not be. Read more about what we do.

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Sunset on a shallow beach in the Bothnian Bay (Photo by Johanna Kantanen, Metsähallitus).