Havana, officially Ciudad de La Habana, is the capital city, major port, and leading commercial centre of Cuba. The city is one of the 15 Cuban provinces. The city/province has 2.1 million inhabitants, the largest city in Cuba and the second largest in the Caribbean region, after Santo Domingo. The city extends mostly westward and southward from the bay, which is entered through a narrow inlet and which divides into three main harbours: Marimelena, Guanabacoa, and Atarés. The sluggish Almendares River traverses the city from south to north, entering the Straits of Florida a few miles west of the bay.