Costa Rica Travel – The lagoon at the Poás volcano has changed to a color not seen in almost 200 years. It’s known as “whale green.” This unusual hue is quite a change from its usual turquoise shade.
The modification in color is due to the injection of sulfur. The volcano has two pockets of activity under the lagoon that are injecting sulfur dioxide constantly.
Both the chemical composition and the light interact to form the color we see. The sulfur dioxide from the fumarole mouth is yellow and it combines with the visible blue light generating the green color we see in the water.
The change is expected to last several days. To date, other temporary color changes included mustard and white.
The activity of the volcano remains low and is always monitored for the protection of visitors. It is open to the public.