The Canal de Castilla and lock 39 Nature · Cubillas de Santa Marta, Campiña del Pisuerga, Valladolid Image of Cubillas de Santa Marta, not of the place itself. The canal crosses the municipal district and here is lock number 39 of the branch, beside the bank of the Pisuerga that serves as the boundary with the neighbouring villages in a flat landscape of poplar groves and irrigated land. Photo: Rastrojo (CC BY-SA 4.0) What to see and do in Cubillas de Santa Marta