This is a flat, traffic-free day on a former railway line that runs from Santader towards the coast. The route covers 40 km with only about 180 m of climbing in total, so gradients are barely noticeable and there are no road junctions to manage along the greenway itself.
You ride at your own pace. There is no target speed, no group pushing the tempo and no need to be fit beyond the ability to sit on a touring bike for a day. Stops for coffee, a picnic or a swim at the coast can be taken as you like.
Among the Santader tours, this is the gentlest full day. The Riverside gravel intro is easy too, but it is on unpaved tracks and is shorter, while the Santader old town e-bike ride is a two-hour city outing. The greenway suits families, casual riders and anyone nervous about cars or hills.