The brightly colored Laguna Colorada, unique in this part of the Bolivian Andes Mountains... The lack of atmospheric haze at great altitude—the lake lies at 4300 m above sea level (14,100 feet)—helps make images of the region especially clear. The strong red-brown color of this shallow, 10 km-long lake is derived from algae that thrive in its salty water. But the lake occasionally has green phases because different algae display different colors, the type being determined by the changing salinity and temperature of the water....