While various contributions by Alexander von Humboldt to different natural sciences are widely recognized, it is not so well known that he was also one of the founders of modern physical marine sciences.

One of his major inputs to this discipline consists in the first ever scientific documentation of the phenomenon called upwelling – which is the key component of the functioning of nearshore ecosystems. During August 1834 Alexander von Humboldt was traveling from Stettin (now Szczecin) to Königsberg (now Kaliningrad), when he measured a strong drop in sea-surface temperature of about 10°C in a certain section off the Polish coast, while further on the temperature again increased to values of about 20°C. It took more than 70 years to properly understand this phenomenon as an application of Ekman’s theory (1905) of currents.

Nowadays marine science in the Baltic Sea – which is by nature interdisciplinary – is carried out beyond national borders and progress in this field requires extensive cooperation of experts from very different areas. This basin has also become a key focus of joint concerns about the health of the ecosystem and about the consequences of climate change, both issues seriously touching many people on the coasts of all seas and oceans.