The tripto catalogue lists 22 lakes – Alpine lakes, glacial lakes in the Black Forest, reservoirs and a brilliant blue karst spring. All are family-friendly, and access to the shore is usually free.
Königssee in Berchtesgaden National Park is hemmed in by mountains like a fjord; electric boats take you to St Bartholomew's, with the trumpet echo along the way. Titisee in the High Black Forest is a glacial lake with a lakeside promenade, boat tours and a circular path. The emerald Eibsee below the Zugspitze has eight islands and a 7.5-kilometre loop trail. Edersee in Hesse is Germany's second-largest reservoir, with a walkable dam wall and the "Edersee Atlantis" ruins at low water. The Blautopf in Blaubeuren is a deep blue karst spring on the edge of the Swabian Jura, and Forggensee near Füssen, Bavaria's largest reservoir, offers boat trips with views towards Neuschwanstein.
Most lakes in the catalogue are in Bavaria (seven) and Baden-Württemberg (four), followed by Lower Saxony with the Steinhuder Meer.
In practice: plan anything from two hours to a full day. Costs are usually limited to parking, boats and lidos: parking at Eibsee costs €10 for up to four hours, or €2.50 for early arrivals; the Königssee boat to St Bartholomew's costs €23.40 return. The swimming season runs from June to September; mountain lakes stay cool even in summer.