Take the train to S-Bahn Mahlsdorf, walking through a patch of residential area, before crossing Wadlow Park. Cross over the main road and then follow the public footpath diagonally across a field. After crossing another road, you will hit the edge of the first of a series of three lakes, which are collectively referred to as Kaulsdorfer Seen. Walk counter-clockwise around Butzer See, then Habermannsee, and finally Elensee. When you are finished picnicking, taking a dip and exploring the lakes, jump back on the path at the edge of Elensee and retrace your steps back to S- Bahn Mahlsdorf.