Ulla (river)
The Ulla is a river in Galicia, Spain.
Its source is sometimes given as Antas de Ulla and sometimes the neighbouring municipality of Monterroso. It flows to the Ría de Arosa estuary near the city of Catoira. Its basin is the second largest in Galicia after the basin of Minho River. Tributaries include the rivers Deza and Arnego.
The river is valued by archaeologists owing to the large number of neolithic artefacts found there. At the outlet of the Ulla River and the mouth of the estuary, called Ría de Arousa, there are two sites where archaeologists have discovered remains including rock carvings. The Ulla River is also important because it is the river in the northwest of the Iberian Peninsula to produce a large number of watery hoards, which were discovered in its lower reaches and its mouth.