SAO MARCOS BAY

Portuguese Baa De So Marcos, bay of the Atlantic Ocean in Maranho estado (state), northeastern Brazil. It is about 60 miles (100 km) long and up to 10 miles (16 km) wide. The bay is actually a drowned river mouth, part of the Mearim River estuary, and it receives the Graja and the Itapicuru rivers. Of the bay's several islands, the largest is So Lus Island, site of the state capital, So Lus.