Is there a ferry that goes from Stockholm to Germany? I have a girlfriend who lives in Stolpe. How long does it take and how much does it cost??

There is no ferry from Stockholm to Germany, unfortunately.

Superfast introduced service between Rostock and Nynäsham a while ago, but apparently they did not generate enough traffic as it lasted for only one season, I believe.

Ferry routes for passengers and their cars between Sweden and Germany exist between Gothenburg and Kiel (operated by Stena Line; they also have a service from Gothenburg to Trave), Trelleborg and Travemuende (operated by TT-Line), Trelleborg and Sassnitz (on the island of Ruegen, seasonal only, I believe) and Trelleborg and Rostock (TT-Line and Scandlines). There are a fewmuende, but that's for trucks only) villages in Germany by the name of Stolpe, all of them located in the three states of Mecklenburg-Vorpommern, Schleswig-Holstein and Brandenburg. Depending on where your girl-friend lives, you could choose your port of arrival.

Both Swedish ports are located in Southern Sweden, though, so you would have to drive there.

Here are the links to the ferry-companies:

http://www.ttline.com/ENGLISH/fnp_start.htm

http://www.stenaline.com/gb/stena_line.html

http://www.scandlines.de/en/main.htm

Finally, here is a nice site by a Danish ferry enthusiast that lists ferry connections from country to country:

http://www.ferry-site.dk/changelang.php?lang=en

Please note that the Stena service between Gothenburg and Travemuende is for trucks and trailers only.