Blue lakes surrounded by forest, lovely bays, wild solitude: in the north of Brandenburg there are lakes whose clarity is reminiscent of crystals. More than 100 of them are in the Stechlin-Ruppiner Land nature park. Above all the Stechlin east of Rheinsberg. It is 69 meters deep, particularly clear and one of the best-researched lakes. Sunbeams play on the backs of silver perch many meters below the surface. In the thicket of riparian vegetation, pike lurk in wait for the right moment to strike at lightning speed. When the water warms up in spring, several male pike will court a female. At his side, they animate the chosen one to give up eggs, scenes that have never been filmed like this before. Large, partly swampy forests surround the Stechlin and shield it from of modern agriculture. Slurry and fertilizers hardly get into the lake. The forest not only protects the lake, one of the fastest birds in the world has recently started breeding here again: the peregrine falcon.