Durban is the third-most populous city in South Africa, after Johannesburg and Cape Town, and the largest city in the province of KwaZulu-Natal. Situated on the east coast of South Africa, on the Natal Bay of the Indian Ocean, Durban is South Africa's busiest port and was formerly named Port Natal. North of the harbour and city centre lies the mouth of the Umgeni River; the flat city centre rises to the hills of the Berea on the west; and to the south, running along the coast, is the Bluff. Durban is the seat of the larger eThekwini Metropolitan Municipality, which spans an area of 2,556 km2 (987 sq mi) and had a population of 4.2 million in 2022, making the metropolitan population one of Africa's largest on the Indian Ocean. Within the city limits, Durban's population was 595,061 in 2011. The city has a humid subtropical climate, with hot, wet summers and mild, dry winters.