Lake Allgäu in the Bavarian Alpine state in Germany turned dark purple on Wednesday. State environment office said purple sulfur bacteria are behind the change in water color.
The purple lake is located in the Faulenbacher Tal Valley, in the city of Füssen. Experts say the purple bacteria necessary for this transformation are found in small bodies of water, and this can also happen in very deep lakes, where there is almost no oxygen in the deeper layers. The color is now weaker and could disappear completely with the next rains.