Lakes around Munich

Coming from the Black Sea in Romania I love to have water around me.
Some friends told me that here in Munich it might be too far to go to the ocean, but that there are very nice lakes around. It would be great if you could tell me which are the best places to go. I am not only interested in the name of the lake, but particularly in where exactly to go at the lakes. Are there nice beaches, beergardens, places for Barbecue that you know?

Thanks for sharing,

Dan