This has to be the most amazing optional excursion that I've done....The whole time you are thinking "I can't believe I'm doing this. It's awesome!" Don't miss this!
In the summer check out some of the great bars that open along the banks of the River Spree. They often out down sand and call themselves 'Strand Bar' - beach bars!
My best advice is to step outside your comfort zone and make an effort to talk to EVERYONE on tour. I made friends from 6 continents on the one tour!!!