Yes, the Eurail Pass fully covers Spain in 2026, but there is a significant "catch" that travelers must be aware of: mandatory seat reservations. Spain’s national rail network, RENFE, requires a reserved seat for almost all high-speed (AVE, Avlo), long-distance (Alvia), and even some regional (Avant) trains. These reservations are not included in the price of your Eurail pass and typically cost between €6 and €10 for domestic trips, or more for international routes like the TGV from Barcelona to Paris. In 2026, you can book these reservations through the Eurail website, the Rail Planner app, or at Spanish train stations. While the pass provides excellent value for traveling between major hubs like Madrid, Barcelona, Seville, and Valencia, the "hop-on, hop-off" flexibility often associated with Eurail is limited in Spain compared to Germany or Switzerland. However, for the local "Cercanías" commuter trains in cities like Madrid or Barcelona, you can often simply show your pass and board without a reservation, making it a versatile tool for both city hopping and regional exploration.