ok. probably the nicest lake that I have found in the area is gossausee, at the base of the dachstein massif. you can walk around it in 1 hour. and it has been raised so you can see old forest trees below the surface. there is also a smaller upper lake but it is quite a hike further up the valley
then there is the Schwarzsee hear strobl/russbach. fuschlsee is a lovely lake with no commercial boating, only electric are allowed. you can walk around that in aprox 3 hours, passing the schlosshotel (very high class). then other small lakes in the wolfgangsee area are the krottensee (v small) and nussensee, (off the beaten track). there are many many that I have not seen yet. Salzburg area has far more lakes and rivers due to being at the base of mountains. munich is in level country therefore few rivers or lakes
here is a tip for you......google "webcam schafberg" (on a clear day... it was in cloud today) and you will be linked to a controllable 360o camera. pan it around and see the lakes! remember to use European time!