A young Turkana man looks out over Lake Turkana, often referred to as the Jade Sea due to the colour of its alkaline water. The barren, windswept country at this southeast corner of the lake is strewn with basalt lava boulders. 160 miles long and between 8 and 27 miles wide, Lake Turkana is one of the oldest and largest lakes of Africa's Great Rift Valley system, and the biggest in Kenya. South Island can be seen across the water.