Feb 29, 2016 - 12:48 PM
Pooja made a great suggestion. You can either do it all by train or train and boat combined. Another option is to take a train to Locarno and the Centovalli train to Domodossola, Italy. Then change to Brig. Then take the local train via Kandersteg to Spiez and finally change to Interlaken.
Both options are included in the Swiss Travel Pass, except for the short leg from Como to Chiasso (Swiss border). Some trains on the Centovalli line require a small surcharge.
You can print the Swiss Travel Pass at home by browsing to www.swissrailways.com/ en and choosing "Online Ticket" when asked for delivery options. Further purchase options are listed here.