Lake Natron is a salt lake in the Arusha Region of northern Tanzania, not far from the border with Kenya. It is shallow — less than 10 feet (3 m) deep — and varies in width depending on its water level. The color of Lake Natron is typical of saline lakes with high evaporation rates, in which salt-loving microorganisms thrive using photosynthesis to make their own food. A by-product of this photosynthesis causes deeper water to turn bright red and shallow parts of the lake to take on a rusty orange color.