You get from Interlaken to Lake Lugano by train through the Alpine pass called Gotthard, but it's the fast way, directly through the tunnel, many kilometers long, so you're in the tunnel for a good 20-30 minutes.
While in Lugano, Jan discovered that you could take a special train (Eurailpass + fees) to Lucerne that followed the more historic way and went only partially through tunnels. It was the Gotthard Express, and provided an exceptional experience. Even before boarding in Lugano, we felt we had drifted into another era of luxury. We were met on the platform, escorted into the train and to our seats by a conductor dedicated specifically to our coach, and offered refreshments. Once we left the station, we had a running commentary and tour from this charming, witty trainman who provided as many geography and history lessons as we wanted. Like a lot of tunnel projects, especially the ones through the Alps, there were delays, injuries and deaths among the teams of diggers, drillers, and the rest, many of whom were Italian laborers.
When a particularly camera-worthy scene was coming up, our conductor came by to escort us back through the train to a car with windows that opened so that we could shoot or video without glare. There were many--steep mountains, gorges, rivers rushing through deep canyons, and more. An antique coach, it also had a wooden, life-sized statue of the Gotthard Pass architect. Because he didn't live to see his creation, his replica is seated where he will forever be able to look out a window!