Notable salt ponds include the San Francisco Bay salt ponds in the United States, the Dead Sea salt ponds in Israel and Jordan and Useless Loop, Western Australia.
Salt evaporation ponds are shallow man-made ponds designed to produce salt from sea water. The seawater is fed into large ponds and water is drawn out through natural evaporation which allows the salt to be subsequently harvested.
Due to variable algal concentrations, vivid colors, from pale green to bright red, are created in the evaporation ponds. The color indicates the salinity of the ponds.
Micro-organisms change their hues as the salinity of the pond increases. In low to mid-salinity ponds, green algae are predominant.
In middle to high salinity ponds, an algae called Dunaliella salina shifts the color to red.
Millions of tiny brine shrimp create an orange cast in mid-salinity ponds. Other bacteria such as Stichococcus also contribute tints.
These colors are especially interesting to airplane passengers or astronauts passing above due to their somewhat artistic formations of shape and color.
Salt evaporation ponds in Peru, in Bulgaria and in Alviso, California on Google Maps.