The paths along the Canal de Castilla make for an easy, flat, peaceful run in Valladolid. Combine paths on both sides of the canal with a pleasant trail in the Botanical Garden, which is a park alongside the east bank canal path. 

Start on the east bank canal path just north of Av. de Gijón. After ~0.3 km, you’ll have the option of staying on the canal path or the adjacent 1.7 km trail through the narrow Botanical Garden (Jardín Botánico). The southern part is more green & shaded, and the northern part is open & scrubby. At the end of the trail, continue on the canal path, crossing the Ronda Este highway, and continue for another ~1.5 km to just past Avenide de Burgos. 

Double back, and just before the Ronda Este, there’s an opportunity to cross over to the west bank path,C. Parva de la Ria. This is part road/part path along the canal, with paved and gravel sections. At the end, cross the small bridge at C. Dársena.