Jul 10, 2014 - 5:50 PM
A Swiss Pass covers traveling within Switzerland only. Details, including the few exceptions to that rule, can be found on the downloadable map.
In your case, Interlaken to Basel Bad Bf is free with a Swiss Pass, so you need a point to point ticket from Basel Bad Bf to Frankfurt.
You can get a Swiss Pass here, and point to point tickets here.
Enjoy the ride!
Last modified on Dec 28, 2014 - 12:55 PM by Arno