During my train trip down to Amsterdam this summer I stopped in Hamburg, since you often have to change trains there when travelling by train in Europe. I decided to stay a night so I would be able to spend some time in the city and visit some places that I had been keen to see. For example, I wanted to visit In guter Gesellschaft, which is a zero waste café situated in Sternschanze.
If I remember correctly, I believe that "In guter Gesellschaft" means "in good company" - which I would say is a perfect name for a café. Since they are a so called zero waste café, their aim is to reduce the environmentally harmful waste produced; they use locally grown and organic products which I would guess are unpackaged as well. Everything is recycled.
When I stepped into the café it honestly felt exactly the way I would a assume a zero waste café would look and feel like. The chairs and tables all looked a bit different and it just had a very relaxed feeling. They offer both vegetarian and vegan food. I only had a cappuccino though, since I visited them in the morning and did not really feel like having breakfast that particular day.
If you are visiting Hamburg I would really recommend that you pay In guter Gesellschaft a visit - especially if you are interested in the concept of zero waste.