Our unique Baltic Sea

The features that make the Baltic Sea so beautiful and special, also make it vulnerable. It’s important that we all do our very best to help our unique sea!

Brackish water. The water in the Baltic Sea is not saline, like sea water in general, but neither is it freshwater, like in the lakes. It is brackish water with salinity somewhere between salty and sweet. Salinity around the Archipelago Sea is only about 0,6%, when salinity in oceans is usually around 3,5%.

Baltic Sea is young. It has developed to its current form through many different phases after the last ice age. The heavy mass of ice weighed down the ground so much it sank, and after the ice melted, the ground began to rise again. The first glimpse of Tunhamn surfaced from the water about 3600 years ago.

A mix of species. Because the Baltic Sea is such a young sea, species haven’t had time to adapt to the brackish water. The species living here are adapted to either marine water or freshwater and are at the limits of their tolerance in the brackish water of the Baltic Sea. Some species adapt to the less than perfect conditions by becoming smaller than their friends in saltier seas. Baltic herring, for example, is just a smaller of a regular herring.

Shallow sea. The Baltic Sea is very shallow for a sea. Its deepest point is only 450 meters, whereas the maximum depth of the Pacific Ocean is over 10 kilometres!

Ice cover. In the winter, the Baltic Sea is by varying degree covered by ice, which is quite unique. It’s not so common around the world to ice-skating to sea!


Taste how the salt concentrations in different seas and oceans taste like! You need one litre of water, salt and a teaspoon. Add salt to water and stir after. It’s not advisable to swallow the saltwater as high intake of salt is bad for health.

The Archipelago Sea, salinity about 0,6 % = add one teaspoon of salt to one litre of water.

The Black Sea, salinity of the surface water about 1,8 % = add two more spoonfuls of salt into the same water.

Typical salinity in oceans, 3,5 % = add yet another four spoonfuls of salt into the same water.

If you dare to, you can try how the Dead Sea tastes like! You can prepare Dead Sea water by adding 10 teaspoons of salt into one decilitre of water.

Did you know that back in the day, harbours were marked with floating anchored barrels? That could be how Tunhamn got its name. Barrel in Swedish is ”en tunna”.

Can you find Söderflada?