Lake Thun (Thunersee) is a big alpine lake, located south of Bern and Luzern. There are many castles to visit, different sports to do, trails to discover with bike or on foot, peaks to reach. Or just stroll down in to the centre of Thun or (a bit more touristic) Interlaken and enjoy town life.
About three waterfalls laketrail: https://www.interlaken.ch/en/tour/three-waterfalls-trail
More ideas on google maps: https://bit.ly/2Yf2XzC
Foto: atelierfabia, Pixabay