The Guardian sends a writer back to Pallars Jussà in western Catalonia 21 years after a honeymoon visit, exploring its wild pre-Pyrenees by the Tren dels Llacs vintage train, mountain bike and kayak. Highlights include the remote Santa Linya halt, the Mirador del Balconet over the Collegats Gorge, paddling Mont-Rebei Canyon, and lakeside stops at Hotel Terradets, with local food, Catalan separatist flags, and a recommendation to hop off the train with a bike.