Yes, the route itself is 100% free for holders of a Swiss Travel Pass or Swiss Travel Pass Flex, but there is a mandatory catch: you must pay for a seat reservation. In 2026, the seat reservation fee is typically CHF 54 per person for a one-way journey in either 1st or 2nd class (depending on your pass type). If you wish to travel in the ultra-luxury Excellence Class, the supplement is significantly higher, costing roughly CHF 540, which includes a multi-course gourmet meal and a concierge service. While the pass covers the "ticket" price (which can be over CHF 150), the reservation is a non-negotiable additional cost that guarantees you a seat with panoramic views on the world's "slowest express train." You can book these reservations up to 93 days in advance on the official Glacier Express website to ensure availability during the popular winter and summer seasons.