Königssee is crossed in silence. The boats that carry you down it run on electric motors, and the loudest sound on board is water against the hull. No engine has been allowed to make noise here since 1909 — a rule first made to keep a royal hunting ground quiet, and kept ever since because it works. The water is clean enough to drink: nothing drains into it, and the emerald surface is among the deepest and purest in Germany, close to 190 metres down. Glaciers gouged this long, narrow trough during the last ice age, giving it the shape of a fjord in the Bavarian Alps. Steep limestone walls climb straight out of the shoreline, and the east face of the Watzmann rises directly above the water, the highest rock wall in the Eastern Alps.
The classic outing is the boat ride itself. Partway down the lake the crew cuts the motor beneath a sheer cliff called the Echowand, raises a flugelhorn, and the notes come ricocheting back across the still water. The boat lands at St. Bartholomä, a red onion-domed pilgrimage church standing alone on a green meadow, reachable no other way than by water. Continue to the far terminus at Salet and a short walk reaches the Obersee, a smaller mirror-lake ringed by rock, and the Röthbachfall — at 470 metres, the highest waterfall in Germany. The air smells of pine and cold stone, cowbells drift down from the high pastures, and a green light seems to rise from the depths. The lake and its shores lie inside Berchtesgaden National Park, protected since 1921.