The bulk of Angola is semiarid elevated savannah. Only two regions, both located in western Angola, have sufficient water for abundant agriculture. Naturally, these regions, the Kwanza River Valley and the central highlands, or "planalto" (Portuguese for "plateau") region, are home to Angola's two dominant ethnicities: the Mbundu and Ovimbundu, respectively. The Kwanza River, which meets the Atlantic Ocean roughly 50 kilometers (31 miles) south of Luanda, is Angola's only notable river. Its river valley offers the only easy access to the country's interior. The planalto is the country's breadbasket. With an average elevation of 1,000-1,700 meters (3,300-5,600 feet) above sea level, the planalto is high enough to capture rainfall and mitigate southern Africa's heat. Eventually, the topography transitions into some of the continent's most distinct and effective geographic barriers. The jungles of the Congo Basin lie to Angola's north. The Namib Desert lies to the south.