Berchtesgaden is a National Park in the far southwest corner of Germany, almost completely surrounded by Austria. It's an easy drive from Salzburg through the town of Berchtesgaden to the National Park. The main access point is a large parking lot on the north end of the Konigsee. There's a small village here selling souvenirs and the basic supplies you need if you're going hiking - like a bacon cheese pretzel. Seriously, we actually took a bacon cheese pretzel on our hike. You have to love Germany.
You can hike from the north end of the lake although most people (including us) choose to take a boat along the lake. This is an incredibly scenic ride on a quiet electric boat. There are several waterfalls visible from the lake, including these two. There are three other destinations accessed by the boats which can allow for some nice one-way hikes.
Most people continue on to St. Bartholoma which is a grassy peninsula with a photogenic onion-domed church on site. There's also a playground here so it was a mandatory stop for us. The final boat stop at the south end of the lake is Salet from where you can hike over a small ridge to the Obersee deeper in the park.
There is a short nature loop at St. Bartholoma as well as a beach of sorts. The water temperature is seriously cold though, at least in May. There is food available at St. Bartholoma as well and some more difficult trails lead up to the large mountains to the west.
This area was once a hunting retreat for kings. As one can see in this picture there isn't much easy terrain once you get away from the lakeshore. However if you do partake of a strenuous hike there's a very nice thermal spa back in Berchtesgaden town called the Watzmann Therme. We probably spent more time in the pools than we did on the trails.