Stump your brain: Can you name Spain’s longest river?

1. Spanish river
2. Flows within Spain
3. Named after the Iberian Peninsula
4. Its delta is a biosphere reserve
5. Second largest river in the Iberian Peninsula
6. Flows through cities such as Logroño, Zaragoza, and Tortosa
7. Has several dams along its course
8. Known for its rich biodiversity
9. Has a total length of over 900 kilometers
10. Originates in the Cantabrian Mountains