Santurtzi is a port town in the province of Biscay, in the autonomous community of Basque Country, Spain. It is located in the Bilbao Abra bay, near the mouth of the Nervión river, on its left bank, 14 km downriver from Bilbao and forms part of the Greater Bilbao agglomeration. It has a population of 45,853 and a land area of 6.77 km². The district of Santurce of the city of San Juan, Puerto Rico derives its name from Santurtzi.