The Esla is a right tributary of the Duero in Spain.
It rises in the Cantabrian Mountains in the Peña Prieta and flows through the provinces of León and Zamora. It is 285 km long. Its main tributaries are Aliste, Porma, Bernesga, Cea, Órbigo and Tera.
During his leading always to the south run the Esla flows through the cities of Riano, Cistierna, Gradefes, and Valencia de Don Juan. Finally, it is dammed to Embalse de Ricobayo and then opens at Muelas del Pan in the Duero.