Yes, the train journey from Interlaken Ost to Grindelwald is 100% covered by the Swiss Travel Pass in 2026. This route is operated by the Berner Oberland Bahn (BOB), and as a pass holder, you do not need to purchase a ticket; you simply board the train and show your pass (digital or paper) to the conductor if asked. This coverage also extends to the train journey from Interlaken to Lauterbrunnen. However, it is important to note that the "free" travel ends at the valley stations of Grindelwald and Lauterbrunnen. If you wish to go higher—for example, taking the cable car to Grindelwald-First or the cogwheel train to the Jungfraujoch—the Swiss Travel Pass usually provides a 50% or 25% discount rather than full coverage. The local buses within Grindelwald are also typically included for free. This makes the Swiss Travel Pass an excellent value for those using Interlaken as a base to explore the Jungfrau region's lower mountain villages.