Yes, the Swiss Travel Pass (often called SwissPass by visitors) fully covers the train journey from Lucerne to Interlaken. This specific route is part of the famous Luzern-Interlaken Express, a premium panoramic train that is one of the highlights of the GoldenPass Line. As long as you have a valid Swiss Travel Pass, you can simply hop on the train and find an available seat without paying any extra fare. While seat reservations are not mandatory for this route, they are highly recommended during the peak summer months (June–August) to ensure you get a window seat for the spectacular views of Lake Brienz and the Brünig Pass. If you choose to make a reservation, there is a small additional fee (usually around 10–14 CHF), but the actual ticket price is $0 for pass holders. It is one of the most cost-effective ways to use the pass, as it combines high-quality transportation with some of the best sightseeing in the Bernese Oberland.