Bangui, close to the country's southern border, lies on the northern banks of the Ubangi River just below a series of rapids that limit major commercial shipping upriver. The only major city located on the river, it covers an area of . The navigable Ubangi River, with the backdrop of lush green hills, turns sharply south below Bangui and connects to the Congo River just south of the equator near Brazzaville as its chief northern tributary. The Ubangi river marks the border between the Central African Republic and the Democratic Republic of the Congo. The Congolese town of Zongo is situated across the river from Bangui. The river flows to the east of downtown Bangui. During the rainy season the discharge in the river is three times higher than during the rest of the year. The city was also known as "La Coquette" (the beautiful city) in the 1970s.