An easy trip with Munich’s public transport for everyone who’s up for a lake or just a fan of the adventure classic „Gabriel Knight 2“ like us is this:
You’ll start at S-Bahn Station Starnberg. You can use a „Munich XXL“ ticket (valid the whole day) and a ride with the regional trains takes approximately 15 Minutes, S-Bahn a little longer (Munich XXL is valid in regional trains, too).
From Starnberg you walk to your right, along the lake (with some interruptions on the street, unfotunately), until you reach Possenhofen Castle, childhood home of Empress Elisabeth („Sissi“). From there, you can take a boat to the opposite shore, to a small village called „Leoni“. Show your Munich XXL ticket and the price per person is just a cheap 2,90 € (in 2018 at least). Check timetables beforehand. No cheaper way to get on the Starnberg lake boat then this!
On the other side of the lake, you walk to your right again, along the shore, until you’ll reach a small alleyway called „Schluchtweg“. It leads you up the bank to a tower dedicated to Otto von Bismarck, first Chancellor of the German Empire. From here on, turn back towards Starnberg but stay up at the hill, getting some nice views over the lake.
When you hit the road again, go down to the chapel, the place where Ludwig II, the last king of Bavaria, died (expect this to be a tourist spot!). From there one is just a walk along the lake and you’ll get back to Starnberg Station.
There’s nothing especially difficult about it. You can use regular shoes. Expect 4 to 6 hours with some sightseeing along the hike and depending on and when how you catch the boat. For easy navigation, you can just download my GPX here