Holding back a mighty river At 62 years old, Lake Kariba, created by the construction of a dam across the Zambezi is a scenic lake in the middle of southern Africa feed by many rivers. The lake is the largest human-created reservoir in the world—a symbol of humans shaping and bending nature towards their own comforts. The Zambezi is the largest of the rivers that feed the lake. Its waters on their way to the Indian ocean, 800 miles (1,290km) downstream of the dam, are held back, if only for a time, by the dam—a 420ft (128m) high arched concrete wall.