Volcanic ash from the Great Rift Valley has collected in local lake basins, creating a network of soda lakes hostile to most organisms. The salt crust changes over time, giving the lake a slightly different appearance each time it is photographed by astronauts or imaged by satellites.

This image simulates natural color, showing where the salt-loving microorganisms have colored the lake’s salt crust red or pink. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) flying on the Terra satellite captured this image on March 8, 2003. Spirulina, a blue-green algae with red pigments, passes its pigments along to the Lesser Flamingoes that feed on the algae and raise their young here. An endemic species of fish, the alkaline tilapia, lives along the edges of the hotspring inlets, and the lake actually derives its color from salt-loving microorganisms that thrive in its alkaline waters. This bright red lake is the world’s most caustic body of water, but not to everything. Lake Natron, in Africa’s Great Rift Valley, practically sends a warning with its color.

Lake natron color