As recently as 10,000 years ago the area of the Baltic Sea was a lake isolated from the world ocean and fed by runoff from the retreating glaciers. It is now the world's largest body of brackish water, connected to the North Sea by the narrow and shallow Danish Straits. With an average depth of only 54m and a very large catchment area from which rivers deliver nutrients and other pollutants, the Baltic Sea ecosystem is a very fragile one. World renowned photographer and filmmaker Mattias Klum followed its uniquely adapted life, highlighting the vulnerability of this important body of water