Most of the continent’s rivers also pose a problem, as they begin in high land and descend in abrupt drops which thwart navigation. For example, the mighty Zambezi may be Africa’s fourth-longest river, running for 1,600 miles, and may be a stunning tourist attraction with its white-water rapids and the Victoria Falls, but as a trade route it is of little use. It flows through six countries, dropping from 4,900 feet to sea level when it reaches the Indian Ocean in Mozambique.
