From Finland to Anatolia, we learn more about great lakes and their importance for the ecosystem. These habitats are often at risk. What strategies are there to preserve these bodies of water?

They are thousands, sometimes even several million years old, some are even made by man. They provide refuges for animals and humans, are important for biodiversity, have aesthetic value and have inspired numerous myths and legends: Lakes. But although their discovery has only just begun, these wonderful water worlds are threatened by pollution, sewage and waste, overfishing and illegal development. In the far north of Europe (Finland's Lake Saimaa), in the central European lowlands (Hungary's Lake Balaton), in Europe's southwest (Alqueva reservoir in Portugal) and in the highlands of Anatolia (Lake Van), we find out more about the special features of various large lakes and their importance for the ecosystem. The series highlights the problems these habitats face in the 21st century, but also the strategies that are being employed to preserve them. This is a captivating four-part series full of stunning landscape shots and unusual discoveries and insights into unique natural wonders far from the tourist hotspots.