Sines is a town and a municipality in Portugal. The municipality, divided into two parishes, has around 14,214 inhabitants in an area of 203.3…Sines is a town and a municipality in Portugal. The municipality, divided into two parishes, has around 14,214 inhabitants in an area of 203.30 km². Sines holds an important oil refinery and several petrochemical industries. It is also a popular beach spot and the main fishing harbour of Alentejo region.